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core/num/
f32.rs

1//! Constants for the `f32` single-precision floating point type.
2//!
3//! *[See also the `f32` primitive type][f32].*
4//!
5//! Mathematically significant numbers are provided in the `consts` sub-module.
6//!
7//! For the constants defined directly in this module
8//! (as distinct from those defined in the `consts` sub-module),
9//! new code should instead use the associated constants
10//! defined directly on the `f32` type.
11
12#![stable(feature = "rust1", since = "1.0.0")]
13
14use crate::convert::FloatToInt;
15use crate::num::FpCategory;
16use crate::panic::const_assert;
17use crate::{cfg_select, intrinsics, mem};
18
19/// The radix or base of the internal representation of `f32`.
20/// Use [`f32::RADIX`] instead.
21///
22/// # Examples
23///
24/// ```rust
25/// // deprecated way
26/// # #[allow(deprecated, deprecated_in_future)]
27/// let r = std::f32::RADIX;
28///
29/// // intended way
30/// let r = f32::RADIX;
31/// ```
32#[stable(feature = "rust1", since = "1.0.0")]
33#[deprecated(since = "TBD", note = "replaced by the `RADIX` associated constant on `f32`")]
34#[rustc_diagnostic_item = "f32_legacy_const_radix"]
35pub const RADIX: u32 = f32::RADIX;
36
37/// Number of significant digits in base 2.
38/// Use [`f32::MANTISSA_DIGITS`] instead.
39///
40/// # Examples
41///
42/// ```rust
43/// // deprecated way
44/// # #[allow(deprecated, deprecated_in_future)]
45/// let d = std::f32::MANTISSA_DIGITS;
46///
47/// // intended way
48/// let d = f32::MANTISSA_DIGITS;
49/// ```
50#[stable(feature = "rust1", since = "1.0.0")]
51#[deprecated(
52    since = "TBD",
53    note = "replaced by the `MANTISSA_DIGITS` associated constant on `f32`"
54)]
55#[rustc_diagnostic_item = "f32_legacy_const_mantissa_dig"]
56pub const MANTISSA_DIGITS: u32 = f32::MANTISSA_DIGITS;
57
58/// Approximate number of significant digits in base 10.
59/// Use [`f32::DIGITS`] instead.
60///
61/// # Examples
62///
63/// ```rust
64/// // deprecated way
65/// # #[allow(deprecated, deprecated_in_future)]
66/// let d = std::f32::DIGITS;
67///
68/// // intended way
69/// let d = f32::DIGITS;
70/// ```
71#[stable(feature = "rust1", since = "1.0.0")]
72#[deprecated(since = "TBD", note = "replaced by the `DIGITS` associated constant on `f32`")]
73#[rustc_diagnostic_item = "f32_legacy_const_digits"]
74pub const DIGITS: u32 = f32::DIGITS;
75
76/// [Machine epsilon] value for `f32`.
77/// Use [`f32::EPSILON`] instead.
78///
79/// This is the difference between `1.0` and the next larger representable number.
80///
81/// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
82///
83/// # Examples
84///
85/// ```rust
86/// // deprecated way
87/// # #[allow(deprecated, deprecated_in_future)]
88/// let e = std::f32::EPSILON;
89///
90/// // intended way
91/// let e = f32::EPSILON;
92/// ```
93#[stable(feature = "rust1", since = "1.0.0")]
94#[deprecated(since = "TBD", note = "replaced by the `EPSILON` associated constant on `f32`")]
95#[rustc_diagnostic_item = "f32_legacy_const_epsilon"]
96pub const EPSILON: f32 = f32::EPSILON;
97
98/// Smallest finite `f32` value.
99/// Use [`f32::MIN`] instead.
100///
101/// # Examples
102///
103/// ```rust
104/// // deprecated way
105/// # #[allow(deprecated, deprecated_in_future)]
106/// let min = std::f32::MIN;
107///
108/// // intended way
109/// let min = f32::MIN;
110/// ```
111#[stable(feature = "rust1", since = "1.0.0")]
112#[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on `f32`")]
113#[rustc_diagnostic_item = "f32_legacy_const_min"]
114pub const MIN: f32 = f32::MIN;
115
116/// Smallest positive normal `f32` value.
117/// Use [`f32::MIN_POSITIVE`] instead.
118///
119/// # Examples
120///
121/// ```rust
122/// // deprecated way
123/// # #[allow(deprecated, deprecated_in_future)]
124/// let min = std::f32::MIN_POSITIVE;
125///
126/// // intended way
127/// let min = f32::MIN_POSITIVE;
128/// ```
129#[stable(feature = "rust1", since = "1.0.0")]
130#[deprecated(since = "TBD", note = "replaced by the `MIN_POSITIVE` associated constant on `f32`")]
131#[rustc_diagnostic_item = "f32_legacy_const_min_positive"]
132pub const MIN_POSITIVE: f32 = f32::MIN_POSITIVE;
133
134/// Largest finite `f32` value.
135/// Use [`f32::MAX`] instead.
136///
137/// # Examples
138///
139/// ```rust
140/// // deprecated way
141/// # #[allow(deprecated, deprecated_in_future)]
142/// let max = std::f32::MAX;
143///
144/// // intended way
145/// let max = f32::MAX;
146/// ```
147#[stable(feature = "rust1", since = "1.0.0")]
148#[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on `f32`")]
149#[rustc_diagnostic_item = "f32_legacy_const_max"]
150pub const MAX: f32 = f32::MAX;
151
152/// One greater than the minimum possible normal power of 2 exponent.
153/// Use [`f32::MIN_EXP`] instead.
154///
155/// # Examples
156///
157/// ```rust
158/// // deprecated way
159/// # #[allow(deprecated, deprecated_in_future)]
160/// let min = std::f32::MIN_EXP;
161///
162/// // intended way
163/// let min = f32::MIN_EXP;
164/// ```
165#[stable(feature = "rust1", since = "1.0.0")]
166#[deprecated(since = "TBD", note = "replaced by the `MIN_EXP` associated constant on `f32`")]
167#[rustc_diagnostic_item = "f32_legacy_const_min_exp"]
168pub const MIN_EXP: i32 = f32::MIN_EXP;
169
170/// Maximum possible power of 2 exponent.
171/// Use [`f32::MAX_EXP`] instead.
172///
173/// # Examples
174///
175/// ```rust
176/// // deprecated way
177/// # #[allow(deprecated, deprecated_in_future)]
178/// let max = std::f32::MAX_EXP;
179///
180/// // intended way
181/// let max = f32::MAX_EXP;
182/// ```
183#[stable(feature = "rust1", since = "1.0.0")]
184#[deprecated(since = "TBD", note = "replaced by the `MAX_EXP` associated constant on `f32`")]
185#[rustc_diagnostic_item = "f32_legacy_const_max_exp"]
186pub const MAX_EXP: i32 = f32::MAX_EXP;
187
188/// Minimum possible normal power of 10 exponent.
189/// Use [`f32::MIN_10_EXP`] instead.
190///
191/// # Examples
192///
193/// ```rust
194/// // deprecated way
195/// # #[allow(deprecated, deprecated_in_future)]
196/// let min = std::f32::MIN_10_EXP;
197///
198/// // intended way
199/// let min = f32::MIN_10_EXP;
200/// ```
201#[stable(feature = "rust1", since = "1.0.0")]
202#[deprecated(since = "TBD", note = "replaced by the `MIN_10_EXP` associated constant on `f32`")]
203#[rustc_diagnostic_item = "f32_legacy_const_min_10_exp"]
204pub const MIN_10_EXP: i32 = f32::MIN_10_EXP;
205
206/// Maximum possible power of 10 exponent.
207/// Use [`f32::MAX_10_EXP`] instead.
208///
209/// # Examples
210///
211/// ```rust
212/// // deprecated way
213/// # #[allow(deprecated, deprecated_in_future)]
214/// let max = std::f32::MAX_10_EXP;
215///
216/// // intended way
217/// let max = f32::MAX_10_EXP;
218/// ```
219#[stable(feature = "rust1", since = "1.0.0")]
220#[deprecated(since = "TBD", note = "replaced by the `MAX_10_EXP` associated constant on `f32`")]
221#[rustc_diagnostic_item = "f32_legacy_const_max_10_exp"]
222pub const MAX_10_EXP: i32 = f32::MAX_10_EXP;
223
224/// Not a Number (NaN).
225/// Use [`f32::NAN`] instead.
226///
227/// # Examples
228///
229/// ```rust
230/// // deprecated way
231/// # #[allow(deprecated, deprecated_in_future)]
232/// let nan = std::f32::NAN;
233///
234/// // intended way
235/// let nan = f32::NAN;
236/// ```
237#[stable(feature = "rust1", since = "1.0.0")]
238#[deprecated(since = "TBD", note = "replaced by the `NAN` associated constant on `f32`")]
239#[rustc_diagnostic_item = "f32_legacy_const_nan"]
240pub const NAN: f32 = f32::NAN;
241
242/// Infinity (∞).
243/// Use [`f32::INFINITY`] instead.
244///
245/// # Examples
246///
247/// ```rust
248/// // deprecated way
249/// # #[allow(deprecated, deprecated_in_future)]
250/// let inf = std::f32::INFINITY;
251///
252/// // intended way
253/// let inf = f32::INFINITY;
254/// ```
255#[stable(feature = "rust1", since = "1.0.0")]
256#[deprecated(since = "TBD", note = "replaced by the `INFINITY` associated constant on `f32`")]
257#[rustc_diagnostic_item = "f32_legacy_const_infinity"]
258pub const INFINITY: f32 = f32::INFINITY;
259
260/// Negative infinity (−∞).
261/// Use [`f32::NEG_INFINITY`] instead.
262///
263/// # Examples
264///
265/// ```rust
266/// // deprecated way
267/// # #[allow(deprecated, deprecated_in_future)]
268/// let ninf = std::f32::NEG_INFINITY;
269///
270/// // intended way
271/// let ninf = f32::NEG_INFINITY;
272/// ```
273#[stable(feature = "rust1", since = "1.0.0")]
274#[deprecated(since = "TBD", note = "replaced by the `NEG_INFINITY` associated constant on `f32`")]
275#[rustc_diagnostic_item = "f32_legacy_const_neg_infinity"]
276pub const NEG_INFINITY: f32 = f32::NEG_INFINITY;
277
278/// Basic mathematical constants.
279#[stable(feature = "rust1", since = "1.0.0")]
280#[rustc_diagnostic_item = "f32_consts_mod"]
281pub mod consts {
282    // FIXME: replace with mathematical constants from cmath.
283
284    /// Archimedes' constant (π)
285    #[stable(feature = "rust1", since = "1.0.0")]
286    pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
287
288    /// The full circle constant (τ)
289    ///
290    /// Equal to 2π.
291    #[stable(feature = "tau_constant", since = "1.47.0")]
292    pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
293
294    /// The golden ratio (φ)
295    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
296    pub const GOLDEN_RATIO: f32 = 1.618033988749894848204586834365638118_f32;
297
298    /// The Euler-Mascheroni constant (γ)
299    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
300    pub const EULER_GAMMA: f32 = 0.577215664901532860606512090082402431_f32;
301
302    /// π/2
303    #[stable(feature = "rust1", since = "1.0.0")]
304    pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
305
306    /// π/3
307    #[stable(feature = "rust1", since = "1.0.0")]
308    pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
309
310    /// π/4
311    #[stable(feature = "rust1", since = "1.0.0")]
312    pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
313
314    /// π/6
315    #[stable(feature = "rust1", since = "1.0.0")]
316    pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
317
318    /// π/8
319    #[stable(feature = "rust1", since = "1.0.0")]
320    pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
321
322    /// 1/π
323    #[stable(feature = "rust1", since = "1.0.0")]
324    pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
325
326    /// 1/sqrt(π)
327    #[unstable(feature = "more_float_constants", issue = "146939")]
328    pub const FRAC_1_SQRT_PI: f32 = 0.564189583547756286948079451560772586_f32;
329
330    /// 1/sqrt(2π)
331    #[doc(alias = "FRAC_1_SQRT_TAU")]
332    #[unstable(feature = "more_float_constants", issue = "146939")]
333    pub const FRAC_1_SQRT_2PI: f32 = 0.398942280401432677939946059934381868_f32;
334
335    /// 2/π
336    #[stable(feature = "rust1", since = "1.0.0")]
337    pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
338
339    /// 2/sqrt(π)
340    #[stable(feature = "rust1", since = "1.0.0")]
341    pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
342
343    /// sqrt(2)
344    #[stable(feature = "rust1", since = "1.0.0")]
345    pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
346
347    /// 1/sqrt(2)
348    #[stable(feature = "rust1", since = "1.0.0")]
349    pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
350
351    /// sqrt(3)
352    #[unstable(feature = "more_float_constants", issue = "146939")]
353    pub const SQRT_3: f32 = 1.732050807568877293527446341505872367_f32;
354
355    /// 1/sqrt(3)
356    #[unstable(feature = "more_float_constants", issue = "146939")]
357    pub const FRAC_1_SQRT_3: f32 = 0.577350269189625764509148780501957456_f32;
358
359    /// sqrt(5)
360    #[unstable(feature = "more_float_constants", issue = "146939")]
361    pub const SQRT_5: f32 = 2.23606797749978969640917366873127623_f32;
362
363    /// 1/sqrt(5)
364    #[unstable(feature = "more_float_constants", issue = "146939")]
365    pub const FRAC_1_SQRT_5: f32 = 0.44721359549995793928183473374625524_f32;
366
367    /// Euler's number (e)
368    #[stable(feature = "rust1", since = "1.0.0")]
369    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
370
371    /// log<sub>2</sub>(e)
372    #[stable(feature = "rust1", since = "1.0.0")]
373    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
374
375    /// log<sub>2</sub>(10)
376    #[stable(feature = "extra_log_consts", since = "1.43.0")]
377    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
378
379    /// log<sub>10</sub>(e)
380    #[stable(feature = "rust1", since = "1.0.0")]
381    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
382
383    /// log<sub>10</sub>(2)
384    #[stable(feature = "extra_log_consts", since = "1.43.0")]
385    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
386
387    /// ln(2)
388    #[stable(feature = "rust1", since = "1.0.0")]
389    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
390
391    /// ln(10)
392    #[stable(feature = "rust1", since = "1.0.0")]
393    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
394}
395
396#[doc(test(attr(allow(unused_features))))]
397impl f32 {
398    /// The radix or base of the internal representation of `f32`.
399    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
400    pub const RADIX: u32 = 2;
401
402    /// The size of this float type in bits.
403    #[unstable(feature = "float_bits_const", issue = "151073")]
404    pub const BITS: u32 = 32;
405
406    /// Number of significant digits in base 2.
407    ///
408    /// Note that the size of the mantissa in the bitwise representation is one
409    /// smaller than this since the leading 1 is not stored explicitly.
410    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
411    pub const MANTISSA_DIGITS: u32 = 24;
412
413    /// Approximate number of significant digits in base 10.
414    ///
415    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
416    /// significant digits can be converted to `f32` and back without loss.
417    ///
418    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
419    ///
420    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
421    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
422    pub const DIGITS: u32 = 6;
423
424    /// [Machine epsilon] value for `f32`.
425    ///
426    /// This is the difference between `1.0` and the next larger representable number.
427    ///
428    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
429    ///
430    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
431    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
432    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
433    #[rustc_diagnostic_item = "f32_epsilon"]
434    pub const EPSILON: f32 = 1.19209290e-07_f32;
435
436    /// Smallest finite `f32` value.
437    ///
438    /// Equal to &minus;[`MAX`].
439    ///
440    /// [`MAX`]: f32::MAX
441    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
442    pub const MIN: f32 = -3.40282347e+38_f32;
443    /// Smallest positive normal `f32` value.
444    ///
445    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
446    ///
447    /// [`MIN_EXP`]: f32::MIN_EXP
448    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
449    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
450    /// Largest finite `f32` value.
451    ///
452    /// Equal to
453    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
454    ///
455    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
456    /// [`MAX_EXP`]: f32::MAX_EXP
457    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
458    pub const MAX: f32 = 3.40282347e+38_f32;
459
460    /// One greater than the minimum possible *normal* power of 2 exponent
461    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
462    ///
463    /// This corresponds to the exact minimum possible *normal* power of 2 exponent
464    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
465    /// In other words, all normal numbers representable by this type are
466    /// greater than or equal to 0.5&nbsp;×&nbsp;2<sup><i>MIN_EXP</i></sup>.
467    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
468    pub const MIN_EXP: i32 = -125;
469    /// One greater than the maximum possible power of 2 exponent
470    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
471    ///
472    /// This corresponds to the exact maximum possible power of 2 exponent
473    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
474    /// In other words, all numbers representable by this type are
475    /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
476    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
477    pub const MAX_EXP: i32 = 128;
478
479    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
480    ///
481    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
482    ///
483    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
484    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
485    pub const MIN_10_EXP: i32 = -37;
486    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
487    ///
488    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
489    ///
490    /// [`MAX`]: f32::MAX
491    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
492    pub const MAX_10_EXP: i32 = 38;
493
494    /// Not a Number (NaN).
495    ///
496    /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
497    /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
498    /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
499    /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
500    /// info.
501    ///
502    /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
503    /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
504    /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
505    /// The concrete bit pattern may change across Rust versions and target platforms.
506    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
507    #[rustc_diagnostic_item = "f32_nan"]
508    #[allow(clippy::eq_op)]
509    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
510    /// Infinity (∞).
511    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
512    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
513    /// Negative infinity (−∞).
514    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
515    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
516
517    /// Maximum integer that can be represented exactly in an [`f32`] value,
518    /// with no other integer converting to the same floating point value.
519    ///
520    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
521    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
522    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
523    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
524    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
525    /// "one-to-one" mapping.
526    ///
527    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
528    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
529    /// ```
530    /// #![feature(float_exact_integer_constants)]
531    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
532    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
533    /// let max_exact_int = f32::MAX_EXACT_INTEGER;
534    /// assert_eq!(max_exact_int, max_exact_int as f32 as i32);
535    /// assert_eq!(max_exact_int + 1, (max_exact_int + 1) as f32 as i32);
536    /// assert_ne!(max_exact_int + 2, (max_exact_int + 2) as f32 as i32);
537    ///
538    /// // Beyond `f32::MAX_EXACT_INTEGER`, multiple integers can map to one float value
539    /// assert_eq!((max_exact_int + 1) as f32, (max_exact_int + 2) as f32);
540    /// # }
541    /// ```
542    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
543    pub const MAX_EXACT_INTEGER: i32 = (1 << Self::MANTISSA_DIGITS) - 1;
544
545    /// Minimum integer that can be represented exactly in an [`f32`] value,
546    /// with no other integer converting to the same floating point value.
547    ///
548    /// For an integer `x` which satisfies `MIN_EXACT_INTEGER <= x <= MAX_EXACT_INTEGER`,
549    /// there is a "one-to-one" mapping between [`i32`] and [`f32`] values.
550    /// `MAX_EXACT_INTEGER + 1` also converts losslessly to [`f32`] and back to
551    /// [`i32`], but `MAX_EXACT_INTEGER + 2` converts to the same [`f32`] value
552    /// (and back to `MAX_EXACT_INTEGER + 1` as an integer) so there is not a
553    /// "one-to-one" mapping.
554    ///
555    /// This constant is equivalent to `-MAX_EXACT_INTEGER`.
556    ///
557    /// [`MAX_EXACT_INTEGER`]: f32::MAX_EXACT_INTEGER
558    /// [`MIN_EXACT_INTEGER`]: f32::MIN_EXACT_INTEGER
559    /// ```
560    /// #![feature(float_exact_integer_constants)]
561    /// # // FIXME(#152635): Float rounding on `i586` does not adhere to IEEE 754
562    /// # #[cfg(not(all(target_arch = "x86", not(target_feature = "sse"))))] {
563    /// let min_exact_int = f32::MIN_EXACT_INTEGER;
564    /// assert_eq!(min_exact_int, min_exact_int as f32 as i32);
565    /// assert_eq!(min_exact_int - 1, (min_exact_int - 1) as f32 as i32);
566    /// assert_ne!(min_exact_int - 2, (min_exact_int - 2) as f32 as i32);
567    ///
568    /// // Below `f32::MIN_EXACT_INTEGER`, multiple integers can map to one float value
569    /// assert_eq!((min_exact_int - 1) as f32, (min_exact_int - 2) as f32);
570    /// # }
571    /// ```
572    #[unstable(feature = "float_exact_integer_constants", issue = "152466")]
573    pub const MIN_EXACT_INTEGER: i32 = -Self::MAX_EXACT_INTEGER;
574
575    /// Sign bit
576    pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
577
578    /// Exponent mask
579    pub(crate) const EXP_MASK: u32 = 0x7f80_0000;
580
581    /// Mantissa mask
582    pub(crate) const MAN_MASK: u32 = 0x007f_ffff;
583
584    /// Minimum representable positive value (min subnormal)
585    const TINY_BITS: u32 = 0x1;
586
587    /// Minimum representable negative value (min negative subnormal)
588    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
589
590    /// Returns `true` if this value is NaN.
591    ///
592    /// ```
593    /// let nan = f32::NAN;
594    /// let f = 7.0_f32;
595    ///
596    /// assert!(nan.is_nan());
597    /// assert!(!f.is_nan());
598    /// ```
599    #[must_use]
600    #[stable(feature = "rust1", since = "1.0.0")]
601    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
602    #[inline]
603    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
604    pub const fn is_nan(self) -> bool {
605        self != self
606    }
607
608    /// Returns `true` if this value is positive infinity or negative infinity, and
609    /// `false` otherwise.
610    ///
611    /// ```
612    /// let f = 7.0f32;
613    /// let inf = f32::INFINITY;
614    /// let neg_inf = f32::NEG_INFINITY;
615    /// let nan = f32::NAN;
616    ///
617    /// assert!(!f.is_infinite());
618    /// assert!(!nan.is_infinite());
619    ///
620    /// assert!(inf.is_infinite());
621    /// assert!(neg_inf.is_infinite());
622    /// ```
623    #[must_use]
624    #[stable(feature = "rust1", since = "1.0.0")]
625    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
626    #[inline]
627    pub const fn is_infinite(self) -> bool {
628        // Getting clever with transmutation can result in incorrect answers on some FPUs
629        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
630        // See https://github.com/rust-lang/rust/issues/72327
631        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
632    }
633
634    /// Returns `true` if this number is neither infinite nor NaN.
635    ///
636    /// ```
637    /// let f = 7.0f32;
638    /// let inf = f32::INFINITY;
639    /// let neg_inf = f32::NEG_INFINITY;
640    /// let nan = f32::NAN;
641    ///
642    /// assert!(f.is_finite());
643    ///
644    /// assert!(!nan.is_finite());
645    /// assert!(!inf.is_finite());
646    /// assert!(!neg_inf.is_finite());
647    /// ```
648    #[must_use]
649    #[stable(feature = "rust1", since = "1.0.0")]
650    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
651    #[inline]
652    pub const fn is_finite(self) -> bool {
653        // There's no need to handle NaN separately: if self is NaN,
654        // the comparison is not true, exactly as desired.
655        self.abs() < Self::INFINITY
656    }
657
658    /// Returns `true` if the number is [subnormal].
659    ///
660    /// ```
661    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
662    /// let max = f32::MAX;
663    /// let lower_than_min = 1.0e-40_f32;
664    /// let zero = 0.0_f32;
665    ///
666    /// assert!(!min.is_subnormal());
667    /// assert!(!max.is_subnormal());
668    ///
669    /// assert!(!zero.is_subnormal());
670    /// assert!(!f32::NAN.is_subnormal());
671    /// assert!(!f32::INFINITY.is_subnormal());
672    /// // Values between `0` and `min` are Subnormal.
673    /// assert!(lower_than_min.is_subnormal());
674    /// ```
675    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
676    #[must_use]
677    #[stable(feature = "is_subnormal", since = "1.53.0")]
678    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
679    #[inline]
680    pub const fn is_subnormal(self) -> bool {
681        matches!(self.classify(), FpCategory::Subnormal)
682    }
683
684    /// Returns `true` if the number is neither zero, infinite,
685    /// [subnormal], or NaN.
686    ///
687    /// ```
688    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
689    /// let max = f32::MAX;
690    /// let lower_than_min = 1.0e-40_f32;
691    /// let zero = 0.0_f32;
692    ///
693    /// assert!(min.is_normal());
694    /// assert!(max.is_normal());
695    ///
696    /// assert!(!zero.is_normal());
697    /// assert!(!f32::NAN.is_normal());
698    /// assert!(!f32::INFINITY.is_normal());
699    /// // Values between `0` and `min` are Subnormal.
700    /// assert!(!lower_than_min.is_normal());
701    /// ```
702    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
703    #[must_use]
704    #[stable(feature = "rust1", since = "1.0.0")]
705    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
706    #[inline]
707    pub const fn is_normal(self) -> bool {
708        matches!(self.classify(), FpCategory::Normal)
709    }
710
711    /// Returns the floating point category of the number. If only one property
712    /// is going to be tested, it is generally faster to use the specific
713    /// predicate instead.
714    ///
715    /// ```
716    /// use std::num::FpCategory;
717    ///
718    /// let num = 12.4_f32;
719    /// let inf = f32::INFINITY;
720    ///
721    /// assert_eq!(num.classify(), FpCategory::Normal);
722    /// assert_eq!(inf.classify(), FpCategory::Infinite);
723    /// ```
724    #[stable(feature = "rust1", since = "1.0.0")]
725    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
726    pub const fn classify(self) -> FpCategory {
727        // We used to have complicated logic here that avoids the simple bit-based tests to work
728        // around buggy codegen for x87 targets (see
729        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
730        // of our tests is able to find any difference between the complicated and the naive
731        // version, so now we are back to the naive version.
732        let b = self.to_bits();
733        match (b & Self::MAN_MASK, b & Self::EXP_MASK) {
734            (0, Self::EXP_MASK) => FpCategory::Infinite,
735            (_, Self::EXP_MASK) => FpCategory::Nan,
736            (0, 0) => FpCategory::Zero,
737            (_, 0) => FpCategory::Subnormal,
738            _ => FpCategory::Normal,
739        }
740    }
741
742    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
743    /// positive sign bit and positive infinity.
744    ///
745    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
746    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
747    /// conserved over arithmetic operations, the result of `is_sign_positive` on
748    /// a NaN might produce an unexpected or non-portable result. See the [specification
749    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
750    /// if you need fully portable behavior (will return `false` for all NaNs).
751    ///
752    /// ```
753    /// let f = 7.0_f32;
754    /// let g = -7.0_f32;
755    ///
756    /// assert!(f.is_sign_positive());
757    /// assert!(!g.is_sign_positive());
758    /// ```
759    #[must_use]
760    #[stable(feature = "rust1", since = "1.0.0")]
761    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
762    #[inline]
763    pub const fn is_sign_positive(self) -> bool {
764        !self.is_sign_negative()
765    }
766
767    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
768    /// negative sign bit and negative infinity.
769    ///
770    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
771    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
772    /// conserved over arithmetic operations, the result of `is_sign_negative` on
773    /// a NaN might produce an unexpected or non-portable result. See the [specification
774    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
775    /// if you need fully portable behavior (will return `false` for all NaNs).
776    ///
777    /// ```
778    /// let f = 7.0f32;
779    /// let g = -7.0f32;
780    ///
781    /// assert!(!f.is_sign_negative());
782    /// assert!(g.is_sign_negative());
783    /// ```
784    #[must_use]
785    #[stable(feature = "rust1", since = "1.0.0")]
786    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
787    #[inline]
788    pub const fn is_sign_negative(self) -> bool {
789        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
790        // applies to zeros and NaNs as well.
791        self.to_bits() & 0x8000_0000 != 0
792    }
793
794    /// Returns the least number greater than `self`.
795    ///
796    /// Let `TINY` be the smallest representable positive `f32`. Then,
797    ///  - if `self.is_nan()`, this returns `self`;
798    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
799    ///  - if `self` is `-TINY`, this returns -0.0;
800    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
801    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
802    ///  - otherwise the unique least value greater than `self` is returned.
803    ///
804    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
805    /// is finite `x == x.next_up().next_down()` also holds.
806    ///
807    /// ```rust
808    /// // f32::EPSILON is the difference between 1.0 and the next number up.
809    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
810    /// // But not for most numbers.
811    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
812    /// assert_eq!(16777216f32.next_up(), 16777218.0);
813    /// ```
814    ///
815    /// This operation corresponds to IEEE-754 `nextUp`.
816    ///
817    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
818    /// [`INFINITY`]: Self::INFINITY
819    /// [`MIN`]: Self::MIN
820    /// [`MAX`]: Self::MAX
821    #[inline]
822    #[doc(alias = "nextUp")]
823    #[stable(feature = "float_next_up_down", since = "1.86.0")]
824    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
825    pub const fn next_up(self) -> Self {
826        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
827        // denormals to zero. This is in general unsound and unsupported, but here
828        // we do our best to still produce the correct result on such targets.
829        let bits = self.to_bits();
830        if self.is_nan() || bits == Self::INFINITY.to_bits() {
831            return self;
832        }
833
834        let abs = bits & !Self::SIGN_MASK;
835        let next_bits = if abs == 0 {
836            Self::TINY_BITS
837        } else if bits == abs {
838            bits + 1
839        } else {
840            bits - 1
841        };
842        Self::from_bits(next_bits)
843    }
844
845    /// Returns the greatest number less than `self`.
846    ///
847    /// Let `TINY` be the smallest representable positive `f32`. Then,
848    ///  - if `self.is_nan()`, this returns `self`;
849    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
850    ///  - if `self` is `TINY`, this returns 0.0;
851    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
852    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
853    ///  - otherwise the unique greatest value less than `self` is returned.
854    ///
855    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
856    /// is finite `x == x.next_down().next_up()` also holds.
857    ///
858    /// ```rust
859    /// let x = 1.0f32;
860    /// // Clamp value into range [0, 1).
861    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
862    /// assert!(clamped < 1.0);
863    /// assert_eq!(clamped.next_up(), 1.0);
864    /// ```
865    ///
866    /// This operation corresponds to IEEE-754 `nextDown`.
867    ///
868    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
869    /// [`INFINITY`]: Self::INFINITY
870    /// [`MIN`]: Self::MIN
871    /// [`MAX`]: Self::MAX
872    #[inline]
873    #[doc(alias = "nextDown")]
874    #[stable(feature = "float_next_up_down", since = "1.86.0")]
875    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
876    pub const fn next_down(self) -> Self {
877        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
878        // denormals to zero. This is in general unsound and unsupported, but here
879        // we do our best to still produce the correct result on such targets.
880        let bits = self.to_bits();
881        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
882            return self;
883        }
884
885        let abs = bits & !Self::SIGN_MASK;
886        let next_bits = if abs == 0 {
887            Self::NEG_TINY_BITS
888        } else if bits == abs {
889            bits - 1
890        } else {
891            bits + 1
892        };
893        Self::from_bits(next_bits)
894    }
895
896    /// Takes the reciprocal (inverse) of a number, `1/x`.
897    ///
898    /// ```
899    /// let x = 2.0_f32;
900    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
901    ///
902    /// assert!(abs_difference <= f32::EPSILON);
903    /// ```
904    #[must_use = "this returns the result of the operation, without modifying the original"]
905    #[stable(feature = "rust1", since = "1.0.0")]
906    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
907    #[inline]
908    pub const fn recip(self) -> f32 {
909        1.0 / self
910    }
911
912    /// Converts radians to degrees.
913    ///
914    /// # Unspecified precision
915    ///
916    /// The precision of this function is non-deterministic. This means it varies by platform,
917    /// Rust version, and can even differ within the same execution from one invocation to the next.
918    ///
919    /// # Examples
920    ///
921    /// ```
922    /// let angle = std::f32::consts::PI;
923    ///
924    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
925    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
926    /// assert!(abs_difference <= f32::EPSILON);
927    /// ```
928    #[must_use = "this returns the result of the operation, \
929                  without modifying the original"]
930    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
931    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
932    #[inline]
933    pub const fn to_degrees(self) -> f32 {
934        // Use a literal to avoid double rounding, consts::PI is already rounded,
935        // and dividing would round again.
936        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
937        self * PIS_IN_180
938    }
939
940    /// Converts degrees to radians.
941    ///
942    /// # Unspecified precision
943    ///
944    /// The precision of this function is non-deterministic. This means it varies by platform,
945    /// Rust version, and can even differ within the same execution from one invocation to the next.
946    ///
947    /// # Examples
948    ///
949    /// ```
950    /// let angle = 180.0f32;
951    ///
952    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
953    ///
954    /// assert!(abs_difference <= f32::EPSILON);
955    /// ```
956    #[must_use = "this returns the result of the operation, \
957                  without modifying the original"]
958    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
959    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
960    #[inline]
961    pub const fn to_radians(self) -> f32 {
962        // The division here is correctly rounded with respect to the true value of π/180.
963        // Although π is irrational and already rounded, the double rounding happens
964        // to produce correct result for f32.
965        const RADS_PER_DEG: f32 = consts::PI / 180.0;
966        self * RADS_PER_DEG
967    }
968
969    /// Returns the maximum of the two numbers, ignoring NaN.
970    ///
971    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
972    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
973    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
974    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
975    /// non-deterministically.
976    ///
977    /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
978    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
979    /// follows the IEEE 754-2008 semantics for `maxNum`.
980    ///
981    /// ```
982    /// let x = 1.0f32;
983    /// let y = 2.0f32;
984    ///
985    /// assert_eq!(x.max(y), y);
986    /// assert_eq!(x.max(f32::NAN), x);
987    /// ```
988    #[must_use = "this returns the result of the comparison, without modifying either input"]
989    #[stable(feature = "rust1", since = "1.0.0")]
990    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
991    #[inline]
992    pub const fn max(self, other: f32) -> f32 {
993        intrinsics::maxnumf32(self, other)
994    }
995
996    /// Returns the minimum of the two numbers, ignoring NaN.
997    ///
998    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
999    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
1000    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
1001    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
1002    /// non-deterministically.
1003    ///
1004    /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
1005    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
1006    /// follows the IEEE 754-2008 semantics for `minNum`.
1007    ///
1008    /// ```
1009    /// let x = 1.0f32;
1010    /// let y = 2.0f32;
1011    ///
1012    /// assert_eq!(x.min(y), x);
1013    /// assert_eq!(x.min(f32::NAN), x);
1014    /// ```
1015    #[must_use = "this returns the result of the comparison, without modifying either input"]
1016    #[stable(feature = "rust1", since = "1.0.0")]
1017    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1018    #[inline]
1019    pub const fn min(self, other: f32) -> f32 {
1020        intrinsics::minnumf32(self, other)
1021    }
1022
1023    /// Returns the maximum of the two numbers, propagating NaN.
1024    ///
1025    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1026    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1027    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1028    /// non-NaN inputs.
1029    ///
1030    /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
1031    /// and which does not reliably order `-0.0` and `+0.0`.
1032    ///
1033    /// This follows the IEEE 754-2019 semantics for `maximum`.
1034    ///
1035    /// ```
1036    /// #![feature(float_minimum_maximum)]
1037    /// let x = 1.0f32;
1038    /// let y = 2.0f32;
1039    ///
1040    /// assert_eq!(x.maximum(y), y);
1041    /// assert!(x.maximum(f32::NAN).is_nan());
1042    /// ```
1043    #[must_use = "this returns the result of the comparison, without modifying either input"]
1044    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1045    #[inline]
1046    pub const fn maximum(self, other: f32) -> f32 {
1047        intrinsics::maximumf32(self, other)
1048    }
1049
1050    /// Returns the minimum of the two numbers, propagating NaN.
1051    ///
1052    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
1053    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
1054    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
1055    /// non-NaN inputs.
1056    ///
1057    /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
1058    /// and which does not reliably order `-0.0` and `+0.0`.
1059    ///
1060    /// This follows the IEEE 754-2019 semantics for `minimum`.
1061    ///
1062    /// ```
1063    /// #![feature(float_minimum_maximum)]
1064    /// let x = 1.0f32;
1065    /// let y = 2.0f32;
1066    ///
1067    /// assert_eq!(x.minimum(y), x);
1068    /// assert!(x.minimum(f32::NAN).is_nan());
1069    /// ```
1070    #[must_use = "this returns the result of the comparison, without modifying either input"]
1071    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1072    #[inline]
1073    pub const fn minimum(self, other: f32) -> f32 {
1074        intrinsics::minimumf32(self, other)
1075    }
1076
1077    /// Calculates the midpoint (average) between `self` and `rhs`.
1078    ///
1079    /// This returns NaN when *either* argument is NaN or if a combination of
1080    /// +inf and -inf is provided as arguments.
1081    ///
1082    /// # Examples
1083    ///
1084    /// ```
1085    /// assert_eq!(1f32.midpoint(4.0), 2.5);
1086    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1087    /// ```
1088    #[inline]
1089    #[doc(alias = "average")]
1090    #[stable(feature = "num_midpoint", since = "1.85.0")]
1091    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1092    pub const fn midpoint(self, other: f32) -> f32 {
1093        cfg_select! {
1094            // Allow faster implementation that have known good 64-bit float
1095            // implementations. Falling back to the branchy code on targets that don't
1096            // have 64-bit hardware floats or buggy implementations.
1097            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1098            any(
1099                target_arch = "x86_64",
1100                target_arch = "aarch64",
1101                all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1102                all(target_arch = "loongarch64", target_feature = "d"),
1103                all(target_arch = "arm", target_feature = "vfp2"),
1104                target_arch = "wasm32",
1105                target_arch = "wasm64",
1106            ) => {
1107                ((self as f64 + other as f64) / 2.0) as f32
1108            }
1109            _ => {
1110                const HI: f32 = f32::MAX / 2.;
1111
1112                let (a, b) = (self, other);
1113                let abs_a = a.abs();
1114                let abs_b = b.abs();
1115
1116                if abs_a <= HI && abs_b <= HI {
1117                    // Overflow is impossible
1118                    (a + b) / 2.
1119                } else {
1120                    (a / 2.) + (b / 2.)
1121                }
1122            }
1123        }
1124    }
1125
1126    /// Rounds toward zero and converts to any primitive integer type,
1127    /// assuming that the value is finite and fits in that type.
1128    ///
1129    /// ```
1130    /// let value = 4.6_f32;
1131    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1132    /// assert_eq!(rounded, 4);
1133    ///
1134    /// let value = -128.9_f32;
1135    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1136    /// assert_eq!(rounded, i8::MIN);
1137    /// ```
1138    ///
1139    /// # Safety
1140    ///
1141    /// The value must:
1142    ///
1143    /// * Not be `NaN`
1144    /// * Not be infinite
1145    /// * Be representable in the return type `Int`, after truncating off its fractional part
1146    #[must_use = "this returns the result of the operation, \
1147                  without modifying the original"]
1148    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1149    #[inline]
1150    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1151    where
1152        Self: FloatToInt<Int>,
1153    {
1154        // SAFETY: the caller must uphold the safety contract for
1155        // `FloatToInt::to_int_unchecked`.
1156        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1157    }
1158
1159    /// Raw transmutation to `u32`.
1160    ///
1161    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1162    ///
1163    /// See [`from_bits`](Self::from_bits) for some discussion of the
1164    /// portability of this operation (there are almost no issues).
1165    ///
1166    /// Note that this function is distinct from `as` casting, which attempts to
1167    /// preserve the *numeric* value, and not the bitwise value.
1168    ///
1169    /// # Examples
1170    ///
1171    /// ```
1172    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1173    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1174    ///
1175    /// ```
1176    #[must_use = "this returns the result of the operation, \
1177                  without modifying the original"]
1178    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1179    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1180    #[inline]
1181    #[allow(unnecessary_transmutes)]
1182    pub const fn to_bits(self) -> u32 {
1183        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1184        unsafe { mem::transmute(self) }
1185    }
1186
1187    /// Raw transmutation from `u32`.
1188    ///
1189    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1190    /// It turns out this is incredibly portable, for two reasons:
1191    ///
1192    /// * Floats and Ints have the same endianness on all supported platforms.
1193    /// * IEEE 754 very precisely specifies the bit layout of floats.
1194    ///
1195    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1196    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1197    /// (notably x86 and ARM) picked the interpretation that was ultimately
1198    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1199    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1200    ///
1201    /// Rather than trying to preserve signaling-ness cross-platform, this
1202    /// implementation favors preserving the exact bits. This means that
1203    /// any payloads encoded in NaNs will be preserved even if the result of
1204    /// this method is sent over the network from an x86 machine to a MIPS one.
1205    ///
1206    /// If the results of this method are only manipulated by the same
1207    /// architecture that produced them, then there is no portability concern.
1208    ///
1209    /// If the input isn't NaN, then there is no portability concern.
1210    ///
1211    /// If you don't care about signalingness (very likely), then there is no
1212    /// portability concern.
1213    ///
1214    /// Note that this function is distinct from `as` casting, which attempts to
1215    /// preserve the *numeric* value, and not the bitwise value.
1216    ///
1217    /// # Examples
1218    ///
1219    /// ```
1220    /// let v = f32::from_bits(0x41480000);
1221    /// assert_eq!(v, 12.5);
1222    /// ```
1223    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1224    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1225    #[must_use]
1226    #[inline]
1227    #[allow(unnecessary_transmutes)]
1228    pub const fn from_bits(v: u32) -> Self {
1229        // It turns out the safety issues with sNaN were overblown! Hooray!
1230        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1231        unsafe { mem::transmute(v) }
1232    }
1233
1234    /// Returns the memory representation of this floating point number as a byte array in
1235    /// big-endian (network) byte order.
1236    ///
1237    /// See [`from_bits`](Self::from_bits) for some discussion of the
1238    /// portability of this operation (there are almost no issues).
1239    ///
1240    /// # Examples
1241    ///
1242    /// ```
1243    /// let bytes = 12.5f32.to_be_bytes();
1244    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1245    /// ```
1246    #[must_use = "this returns the result of the operation, \
1247                  without modifying the original"]
1248    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1249    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1250    #[inline]
1251    pub const fn to_be_bytes(self) -> [u8; 4] {
1252        self.to_bits().to_be_bytes()
1253    }
1254
1255    /// Returns the memory representation of this floating point number as a byte array in
1256    /// little-endian byte order.
1257    ///
1258    /// See [`from_bits`](Self::from_bits) for some discussion of the
1259    /// portability of this operation (there are almost no issues).
1260    ///
1261    /// # Examples
1262    ///
1263    /// ```
1264    /// let bytes = 12.5f32.to_le_bytes();
1265    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1266    /// ```
1267    #[must_use = "this returns the result of the operation, \
1268                  without modifying the original"]
1269    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1270    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1271    #[inline]
1272    pub const fn to_le_bytes(self) -> [u8; 4] {
1273        self.to_bits().to_le_bytes()
1274    }
1275
1276    /// Returns the memory representation of this floating point number as a byte array in
1277    /// native byte order.
1278    ///
1279    /// As the target platform's native endianness is used, portable code
1280    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1281    ///
1282    /// [`to_be_bytes`]: f32::to_be_bytes
1283    /// [`to_le_bytes`]: f32::to_le_bytes
1284    ///
1285    /// See [`from_bits`](Self::from_bits) for some discussion of the
1286    /// portability of this operation (there are almost no issues).
1287    ///
1288    /// # Examples
1289    ///
1290    /// ```
1291    /// let bytes = 12.5f32.to_ne_bytes();
1292    /// assert_eq!(
1293    ///     bytes,
1294    ///     if cfg!(target_endian = "big") {
1295    ///         [0x41, 0x48, 0x00, 0x00]
1296    ///     } else {
1297    ///         [0x00, 0x00, 0x48, 0x41]
1298    ///     }
1299    /// );
1300    /// ```
1301    #[must_use = "this returns the result of the operation, \
1302                  without modifying the original"]
1303    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1304    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1305    #[inline]
1306    pub const fn to_ne_bytes(self) -> [u8; 4] {
1307        self.to_bits().to_ne_bytes()
1308    }
1309
1310    /// Creates a floating point value from its representation as a byte array in big endian.
1311    ///
1312    /// See [`from_bits`](Self::from_bits) for some discussion of the
1313    /// portability of this operation (there are almost no issues).
1314    ///
1315    /// # Examples
1316    ///
1317    /// ```
1318    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1319    /// assert_eq!(value, 12.5);
1320    /// ```
1321    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1322    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1323    #[must_use]
1324    #[inline]
1325    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1326        Self::from_bits(u32::from_be_bytes(bytes))
1327    }
1328
1329    /// Creates a floating point value from its representation as a byte array in little endian.
1330    ///
1331    /// See [`from_bits`](Self::from_bits) for some discussion of the
1332    /// portability of this operation (there are almost no issues).
1333    ///
1334    /// # Examples
1335    ///
1336    /// ```
1337    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1338    /// assert_eq!(value, 12.5);
1339    /// ```
1340    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1341    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1342    #[must_use]
1343    #[inline]
1344    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1345        Self::from_bits(u32::from_le_bytes(bytes))
1346    }
1347
1348    /// Creates a floating point value from its representation as a byte array in native endian.
1349    ///
1350    /// As the target platform's native endianness is used, portable code
1351    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1352    /// appropriate instead.
1353    ///
1354    /// [`from_be_bytes`]: f32::from_be_bytes
1355    /// [`from_le_bytes`]: f32::from_le_bytes
1356    ///
1357    /// See [`from_bits`](Self::from_bits) for some discussion of the
1358    /// portability of this operation (there are almost no issues).
1359    ///
1360    /// # Examples
1361    ///
1362    /// ```
1363    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1364    ///     [0x41, 0x48, 0x00, 0x00]
1365    /// } else {
1366    ///     [0x00, 0x00, 0x48, 0x41]
1367    /// });
1368    /// assert_eq!(value, 12.5);
1369    /// ```
1370    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1371    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1372    #[must_use]
1373    #[inline]
1374    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1375        Self::from_bits(u32::from_ne_bytes(bytes))
1376    }
1377
1378    /// Returns the ordering between `self` and `other`.
1379    ///
1380    /// Unlike the standard partial comparison between floating point numbers,
1381    /// this comparison always produces an ordering in accordance to
1382    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1383    /// floating point standard. The values are ordered in the following sequence:
1384    ///
1385    /// - negative quiet NaN
1386    /// - negative signaling NaN
1387    /// - negative infinity
1388    /// - negative numbers
1389    /// - negative subnormal numbers
1390    /// - negative zero
1391    /// - positive zero
1392    /// - positive subnormal numbers
1393    /// - positive numbers
1394    /// - positive infinity
1395    /// - positive signaling NaN
1396    /// - positive quiet NaN.
1397    ///
1398    /// The ordering established by this function does not always agree with the
1399    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1400    /// they consider negative and positive zero equal, while `total_cmp`
1401    /// doesn't.
1402    ///
1403    /// The interpretation of the signaling NaN bit follows the definition in
1404    /// the IEEE 754 standard, which may not match the interpretation by some of
1405    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1406    ///
1407    /// # Example
1408    ///
1409    /// ```
1410    /// struct GoodBoy {
1411    ///     name: String,
1412    ///     weight: f32,
1413    /// }
1414    ///
1415    /// let mut bois = vec![
1416    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1417    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1418    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1419    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1420    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1421    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1422    /// ];
1423    ///
1424    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1425    ///
1426    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1427    /// if f32::NAN.is_sign_negative() {
1428    ///     assert!(bois.into_iter().map(|b| b.weight)
1429    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1430    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1431    /// } else {
1432    ///     assert!(bois.into_iter().map(|b| b.weight)
1433    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1434    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1435    /// }
1436    /// ```
1437    #[stable(feature = "total_cmp", since = "1.62.0")]
1438    #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1439    #[must_use]
1440    #[inline]
1441    pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1442        let mut left = self.to_bits() as i32;
1443        let mut right = other.to_bits() as i32;
1444
1445        // In case of negatives, flip all the bits except the sign
1446        // to achieve a similar layout as two's complement integers
1447        //
1448        // Why does this work? IEEE 754 floats consist of three fields:
1449        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1450        // fields as a whole have the property that their bitwise order is
1451        // equal to the numeric magnitude where the magnitude is defined.
1452        // The magnitude is not normally defined on NaN values, but
1453        // IEEE 754 totalOrder defines the NaN values also to follow the
1454        // bitwise order. This leads to order explained in the doc comment.
1455        // However, the representation of magnitude is the same for negative
1456        // and positive numbers – only the sign bit is different.
1457        // To easily compare the floats as signed integers, we need to
1458        // flip the exponent and mantissa bits in case of negative numbers.
1459        // We effectively convert the numbers to "two's complement" form.
1460        //
1461        // To do the flipping, we construct a mask and XOR against it.
1462        // We branchlessly calculate an "all-ones except for the sign bit"
1463        // mask from negative-signed values: right shifting sign-extends
1464        // the integer, so we "fill" the mask with sign bits, and then
1465        // convert to unsigned to push one more zero bit.
1466        // On positive values, the mask is all zeros, so it's a no-op.
1467        left ^= (((left >> 31) as u32) >> 1) as i32;
1468        right ^= (((right >> 31) as u32) >> 1) as i32;
1469
1470        left.cmp(&right)
1471    }
1472
1473    /// Restrict a value to a certain interval unless it is NaN.
1474    ///
1475    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1476    /// less than `min`. Otherwise this returns `self`.
1477    ///
1478    /// Note that this function returns NaN if the initial value was NaN as
1479    /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1480    /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1481    ///
1482    /// # Panics
1483    ///
1484    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1485    ///
1486    /// # Examples
1487    ///
1488    /// ```
1489    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1490    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1491    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1492    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1493    ///
1494    /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1495    /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1496    /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1497    /// // This is definitely a negative zero.
1498    /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1499    /// ```
1500    #[must_use = "method returns a new number and does not mutate the original value"]
1501    #[stable(feature = "clamp", since = "1.50.0")]
1502    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1503    #[inline]
1504    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1505        const_assert!(
1506            min <= max,
1507            "min > max, or either was NaN",
1508            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1509            min: f32,
1510            max: f32,
1511        );
1512
1513        if self < min {
1514            self = min;
1515        }
1516        if self > max {
1517            self = max;
1518        }
1519        self
1520    }
1521
1522    /// Clamps this number to a symmetric range centered around zero.
1523    ///
1524    /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1525    ///
1526    /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1527    /// explicit about the intent.
1528    ///
1529    /// # Panics
1530    ///
1531    /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1532    ///
1533    /// # Examples
1534    ///
1535    /// ```
1536    /// #![feature(clamp_magnitude)]
1537    /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1538    /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1539    /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1540    /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1541    /// ```
1542    #[must_use = "this returns the clamped value and does not modify the original"]
1543    #[unstable(feature = "clamp_magnitude", issue = "148519")]
1544    #[inline]
1545    pub fn clamp_magnitude(self, limit: f32) -> f32 {
1546        assert!(limit >= 0.0, "limit must be non-negative");
1547        let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1548        self.clamp(-limit, limit)
1549    }
1550
1551    /// Computes the absolute value of `self`.
1552    ///
1553    /// This function always returns the precise result.
1554    ///
1555    /// # Examples
1556    ///
1557    /// ```
1558    /// let x = 3.5_f32;
1559    /// let y = -3.5_f32;
1560    ///
1561    /// assert_eq!(x.abs(), x);
1562    /// assert_eq!(y.abs(), -y);
1563    ///
1564    /// assert!(f32::NAN.abs().is_nan());
1565    /// ```
1566    #[must_use = "method returns a new number and does not mutate the original value"]
1567    #[stable(feature = "rust1", since = "1.0.0")]
1568    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1569    #[inline]
1570    pub const fn abs(self) -> f32 {
1571        intrinsics::fabsf32(self)
1572    }
1573
1574    /// Returns a number that represents the sign of `self`.
1575    ///
1576    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1577    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1578    /// - NaN if the number is NaN
1579    ///
1580    /// # Examples
1581    ///
1582    /// ```
1583    /// let f = 3.5_f32;
1584    ///
1585    /// assert_eq!(f.signum(), 1.0);
1586    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1587    ///
1588    /// assert!(f32::NAN.signum().is_nan());
1589    /// ```
1590    #[must_use = "method returns a new number and does not mutate the original value"]
1591    #[stable(feature = "rust1", since = "1.0.0")]
1592    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1593    #[inline]
1594    pub const fn signum(self) -> f32 {
1595        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1596    }
1597
1598    /// Returns a number composed of the magnitude of `self` and the sign of
1599    /// `sign`.
1600    ///
1601    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1602    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1603    /// returned.
1604    ///
1605    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1606    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1607    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1608    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1609    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1610    /// info.
1611    ///
1612    /// # Examples
1613    ///
1614    /// ```
1615    /// let f = 3.5_f32;
1616    ///
1617    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1618    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1619    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1620    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1621    ///
1622    /// assert!(f32::NAN.copysign(1.0).is_nan());
1623    /// ```
1624    #[must_use = "method returns a new number and does not mutate the original value"]
1625    #[inline]
1626    #[stable(feature = "copysign", since = "1.35.0")]
1627    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1628    pub const fn copysign(self, sign: f32) -> f32 {
1629        intrinsics::copysignf32(self, sign)
1630    }
1631
1632    /// Float addition that allows optimizations based on algebraic rules.
1633    ///
1634    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1635    #[must_use = "method returns a new number and does not mutate the original value"]
1636    #[unstable(feature = "float_algebraic", issue = "136469")]
1637    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1638    #[inline]
1639    pub const fn algebraic_add(self, rhs: f32) -> f32 {
1640        intrinsics::fadd_algebraic(self, rhs)
1641    }
1642
1643    /// Float subtraction that allows optimizations based on algebraic rules.
1644    ///
1645    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1646    #[must_use = "method returns a new number and does not mutate the original value"]
1647    #[unstable(feature = "float_algebraic", issue = "136469")]
1648    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1649    #[inline]
1650    pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1651        intrinsics::fsub_algebraic(self, rhs)
1652    }
1653
1654    /// Float multiplication that allows optimizations based on algebraic rules.
1655    ///
1656    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1657    #[must_use = "method returns a new number and does not mutate the original value"]
1658    #[unstable(feature = "float_algebraic", issue = "136469")]
1659    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1660    #[inline]
1661    pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1662        intrinsics::fmul_algebraic(self, rhs)
1663    }
1664
1665    /// Float division that allows optimizations based on algebraic rules.
1666    ///
1667    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1668    #[must_use = "method returns a new number and does not mutate the original value"]
1669    #[unstable(feature = "float_algebraic", issue = "136469")]
1670    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1671    #[inline]
1672    pub const fn algebraic_div(self, rhs: f32) -> f32 {
1673        intrinsics::fdiv_algebraic(self, rhs)
1674    }
1675
1676    /// Float remainder that allows optimizations based on algebraic rules.
1677    ///
1678    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1679    #[must_use = "method returns a new number and does not mutate the original value"]
1680    #[unstable(feature = "float_algebraic", issue = "136469")]
1681    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1682    #[inline]
1683    pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1684        intrinsics::frem_algebraic(self, rhs)
1685    }
1686}
1687
1688/// Experimental implementations of floating point functions in `core`.
1689///
1690/// _The standalone functions in this module are for testing only.
1691/// They will be stabilized as inherent methods._
1692#[unstable(feature = "core_float_math", issue = "137578")]
1693pub mod math {
1694    use crate::intrinsics;
1695    use crate::num::imp::libm;
1696
1697    /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1698    ///
1699    /// # Examples
1700    ///
1701    /// ```
1702    /// #![feature(core_float_math)]
1703    ///
1704    /// use core::f32;
1705    ///
1706    /// let f = 3.7_f32;
1707    /// let g = 3.0_f32;
1708    /// let h = -3.7_f32;
1709    ///
1710    /// assert_eq!(f32::math::floor(f), 3.0);
1711    /// assert_eq!(f32::math::floor(g), 3.0);
1712    /// assert_eq!(f32::math::floor(h), -4.0);
1713    /// ```
1714    ///
1715    /// _This standalone function is for testing only.
1716    /// It will be stabilized as an inherent method._
1717    ///
1718    /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1719    #[inline]
1720    #[unstable(feature = "core_float_math", issue = "137578")]
1721    #[must_use = "method returns a new number and does not mutate the original value"]
1722    pub const fn floor(x: f32) -> f32 {
1723        intrinsics::floorf32(x)
1724    }
1725
1726    /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1727    ///
1728    /// # Examples
1729    ///
1730    /// ```
1731    /// #![feature(core_float_math)]
1732    ///
1733    /// use core::f32;
1734    ///
1735    /// let f = 3.01_f32;
1736    /// let g = 4.0_f32;
1737    ///
1738    /// assert_eq!(f32::math::ceil(f), 4.0);
1739    /// assert_eq!(f32::math::ceil(g), 4.0);
1740    /// ```
1741    ///
1742    /// _This standalone function is for testing only.
1743    /// It will be stabilized as an inherent method._
1744    ///
1745    /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1746    #[inline]
1747    #[doc(alias = "ceiling")]
1748    #[must_use = "method returns a new number and does not mutate the original value"]
1749    #[unstable(feature = "core_float_math", issue = "137578")]
1750    pub const fn ceil(x: f32) -> f32 {
1751        intrinsics::ceilf32(x)
1752    }
1753
1754    /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1755    ///
1756    /// # Examples
1757    ///
1758    /// ```
1759    /// #![feature(core_float_math)]
1760    ///
1761    /// use core::f32;
1762    ///
1763    /// let f = 3.3_f32;
1764    /// let g = -3.3_f32;
1765    /// let h = -3.7_f32;
1766    /// let i = 3.5_f32;
1767    /// let j = 4.5_f32;
1768    ///
1769    /// assert_eq!(f32::math::round(f), 3.0);
1770    /// assert_eq!(f32::math::round(g), -3.0);
1771    /// assert_eq!(f32::math::round(h), -4.0);
1772    /// assert_eq!(f32::math::round(i), 4.0);
1773    /// assert_eq!(f32::math::round(j), 5.0);
1774    /// ```
1775    ///
1776    /// _This standalone function is for testing only.
1777    /// It will be stabilized as an inherent method._
1778    ///
1779    /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1780    #[inline]
1781    #[unstable(feature = "core_float_math", issue = "137578")]
1782    #[must_use = "method returns a new number and does not mutate the original value"]
1783    pub const fn round(x: f32) -> f32 {
1784        intrinsics::roundf32(x)
1785    }
1786
1787    /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1788    /// details.
1789    ///
1790    /// # Examples
1791    ///
1792    /// ```
1793    /// #![feature(core_float_math)]
1794    ///
1795    /// use core::f32;
1796    ///
1797    /// let f = 3.3_f32;
1798    /// let g = -3.3_f32;
1799    /// let h = 3.5_f32;
1800    /// let i = 4.5_f32;
1801    ///
1802    /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1803    /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1804    /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1805    /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1806    /// ```
1807    ///
1808    /// _This standalone function is for testing only.
1809    /// It will be stabilized as an inherent method._
1810    ///
1811    /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1812    #[inline]
1813    #[unstable(feature = "core_float_math", issue = "137578")]
1814    #[must_use = "method returns a new number and does not mutate the original value"]
1815    pub const fn round_ties_even(x: f32) -> f32 {
1816        intrinsics::round_ties_even_f32(x)
1817    }
1818
1819    /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1820    ///
1821    /// # Examples
1822    ///
1823    /// ```
1824    /// #![feature(core_float_math)]
1825    ///
1826    /// use core::f32;
1827    ///
1828    /// let f = 3.7_f32;
1829    /// let g = 3.0_f32;
1830    /// let h = -3.7_f32;
1831    ///
1832    /// assert_eq!(f32::math::trunc(f), 3.0);
1833    /// assert_eq!(f32::math::trunc(g), 3.0);
1834    /// assert_eq!(f32::math::trunc(h), -3.0);
1835    /// ```
1836    ///
1837    /// _This standalone function is for testing only.
1838    /// It will be stabilized as an inherent method._
1839    ///
1840    /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1841    #[inline]
1842    #[doc(alias = "truncate")]
1843    #[must_use = "method returns a new number and does not mutate the original value"]
1844    #[unstable(feature = "core_float_math", issue = "137578")]
1845    pub const fn trunc(x: f32) -> f32 {
1846        intrinsics::truncf32(x)
1847    }
1848
1849    /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1850    ///
1851    /// # Examples
1852    ///
1853    /// ```
1854    /// #![feature(core_float_math)]
1855    ///
1856    /// use core::f32;
1857    ///
1858    /// let x = 3.6_f32;
1859    /// let y = -3.6_f32;
1860    /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1861    /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1862    ///
1863    /// assert!(abs_difference_x <= f32::EPSILON);
1864    /// assert!(abs_difference_y <= f32::EPSILON);
1865    /// ```
1866    ///
1867    /// _This standalone function is for testing only.
1868    /// It will be stabilized as an inherent method._
1869    ///
1870    /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1871    #[inline]
1872    #[unstable(feature = "core_float_math", issue = "137578")]
1873    #[must_use = "method returns a new number and does not mutate the original value"]
1874    pub const fn fract(x: f32) -> f32 {
1875        x - trunc(x)
1876    }
1877
1878    /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1879    ///
1880    /// # Examples
1881    ///
1882    /// ```
1883    /// # #![allow(unused_features)]
1884    /// #![feature(core_float_math)]
1885    ///
1886    /// # // FIXME(#140515): mingw has an incorrect fma
1887    /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1888    /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1889    /// use core::f32;
1890    ///
1891    /// let m = 10.0_f32;
1892    /// let x = 4.0_f32;
1893    /// let b = 60.0_f32;
1894    ///
1895    /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1896    /// assert_eq!(m * x + b, 100.0);
1897    ///
1898    /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1899    /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1900    /// let minus_one = -1.0_f32;
1901    ///
1902    /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1903    /// assert_eq!(
1904    ///     f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1905    ///     -f32::EPSILON * f32::EPSILON
1906    /// );
1907    /// // Different rounding with the non-fused multiply and add.
1908    /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1909    /// # }
1910    /// ```
1911    ///
1912    /// _This standalone function is for testing only.
1913    /// It will be stabilized as an inherent method._
1914    ///
1915    /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1916    #[inline]
1917    #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1918    #[must_use = "method returns a new number and does not mutate the original value"]
1919    #[unstable(feature = "core_float_math", issue = "137578")]
1920    pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1921        intrinsics::fmaf32(x, y, z)
1922    }
1923
1924    /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1925    ///
1926    /// # Examples
1927    ///
1928    /// ```
1929    /// #![feature(core_float_math)]
1930    ///
1931    /// use core::f32;
1932    ///
1933    /// let a: f32 = 7.0;
1934    /// let b = 4.0;
1935    /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
1936    /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
1937    /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
1938    /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
1939    /// ```
1940    ///
1941    /// _This standalone function is for testing only.
1942    /// It will be stabilized as an inherent method._
1943    ///
1944    /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
1945    #[inline]
1946    #[unstable(feature = "core_float_math", issue = "137578")]
1947    #[must_use = "method returns a new number and does not mutate the original value"]
1948    pub fn div_euclid(x: f32, rhs: f32) -> f32 {
1949        let q = trunc(x / rhs);
1950        if x % rhs < 0.0 {
1951            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
1952        }
1953        q
1954    }
1955
1956    /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
1957    ///
1958    /// # Examples
1959    ///
1960    /// ```
1961    /// #![feature(core_float_math)]
1962    ///
1963    /// use core::f32;
1964    ///
1965    /// let a: f32 = 7.0;
1966    /// let b = 4.0;
1967    /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
1968    /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
1969    /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
1970    /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
1971    /// // limitation due to round-off error
1972    /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
1973    /// ```
1974    ///
1975    /// _This standalone function is for testing only.
1976    /// It will be stabilized as an inherent method._
1977    ///
1978    /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
1979    #[inline]
1980    #[doc(alias = "modulo", alias = "mod")]
1981    #[unstable(feature = "core_float_math", issue = "137578")]
1982    #[must_use = "method returns a new number and does not mutate the original value"]
1983    pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
1984        let r = x % rhs;
1985        if r < 0.0 { r + rhs.abs() } else { r }
1986    }
1987
1988    /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
1989    ///
1990    /// # Examples
1991    ///
1992    /// ```
1993    /// #![feature(core_float_math)]
1994    ///
1995    /// use core::f32;
1996    ///
1997    /// let x = 2.0_f32;
1998    /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
1999    /// assert!(abs_difference <= 1e-5);
2000    ///
2001    /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
2002    /// ```
2003    ///
2004    /// _This standalone function is for testing only.
2005    /// It will be stabilized as an inherent method._
2006    ///
2007    /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
2008    #[inline]
2009    #[must_use = "method returns a new number and does not mutate the original value"]
2010    #[unstable(feature = "core_float_math", issue = "137578")]
2011    pub fn powi(x: f32, n: i32) -> f32 {
2012        intrinsics::powif32(x, n)
2013    }
2014
2015    /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
2016    ///
2017    /// # Examples
2018    ///
2019    /// ```
2020    /// #![feature(core_float_math)]
2021    ///
2022    /// use core::f32;
2023    ///
2024    /// let positive = 4.0_f32;
2025    /// let negative = -4.0_f32;
2026    /// let negative_zero = -0.0_f32;
2027    ///
2028    /// assert_eq!(f32::math::sqrt(positive), 2.0);
2029    /// assert!(f32::math::sqrt(negative).is_nan());
2030    /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
2031    /// ```
2032    ///
2033    /// _This standalone function is for testing only.
2034    /// It will be stabilized as an inherent method._
2035    ///
2036    /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
2037    #[inline]
2038    #[doc(alias = "squareRoot")]
2039    #[unstable(feature = "core_float_math", issue = "137578")]
2040    #[must_use = "method returns a new number and does not mutate the original value"]
2041    pub fn sqrt(x: f32) -> f32 {
2042        intrinsics::sqrtf32(x)
2043    }
2044
2045    /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
2046    ///
2047    /// # Examples
2048    ///
2049    /// ```
2050    /// #![feature(core_float_math)]
2051    ///
2052    /// use core::f32;
2053    ///
2054    /// let x = 3.0f32;
2055    /// let y = -3.0f32;
2056    ///
2057    /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
2058    /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
2059    ///
2060    /// assert!(abs_difference_x <= 1e-6);
2061    /// assert!(abs_difference_y <= 1e-6);
2062    /// ```
2063    ///
2064    /// _This standalone function is for testing only.
2065    /// It will be stabilized as an inherent method._
2066    ///
2067    /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2068    #[inline]
2069    #[stable(feature = "rust1", since = "1.0.0")]
2070    #[deprecated(
2071        since = "1.10.0",
2072        note = "you probably meant `(self - other).abs()`: \
2073            this operation is `(self - other).max(0.0)` \
2074            except that `abs_sub` also propagates NaNs (also \
2075            known as `fdimf` in C). If you truly need the positive \
2076            difference, consider using that expression or the C function \
2077            `fdimf`, depending on how you wish to handle NaN (please consider \
2078            filing an issue describing your use-case too)."
2079    )]
2080    #[must_use = "method returns a new number and does not mutate the original value"]
2081    pub fn abs_sub(x: f32, other: f32) -> f32 {
2082        libm::fdimf(x, other)
2083    }
2084
2085    /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2086    ///
2087    /// # Unspecified precision
2088    ///
2089    /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2090    /// can even differ within the same execution from one invocation to the next.
2091    /// This function currently corresponds to the `cbrtf` from libc on Unix
2092    /// and Windows. Note that this might change in the future.
2093    ///
2094    /// # Examples
2095    ///
2096    /// ```
2097    /// #![feature(core_float_math)]
2098    ///
2099    /// use core::f32;
2100    ///
2101    /// let x = 8.0f32;
2102    ///
2103    /// // x^(1/3) - 2 == 0
2104    /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2105    ///
2106    /// assert!(abs_difference <= 1e-6);
2107    /// ```
2108    ///
2109    /// _This standalone function is for testing only.
2110    /// It will be stabilized as an inherent method._
2111    ///
2112    /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2113    #[inline]
2114    #[must_use = "method returns a new number and does not mutate the original value"]
2115    #[unstable(feature = "core_float_math", issue = "137578")]
2116    pub fn cbrt(x: f32) -> f32 {
2117        libm::cbrtf(x)
2118    }
2119}