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    #[unstable(feature = "more_float_constants", issue = "146939")]
296    pub const PHI: f32 = 1.618033988749894848204586834365638118_f32;
297
298    /// The Euler-Mascheroni constant (γ)
299    #[unstable(feature = "more_float_constants", issue = "146939")]
300    pub const EGAMMA: 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    /// Euler's number (e)
360    #[stable(feature = "rust1", since = "1.0.0")]
361    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
362
363    /// log<sub>2</sub>(e)
364    #[stable(feature = "rust1", since = "1.0.0")]
365    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
366
367    /// log<sub>2</sub>(10)
368    #[stable(feature = "extra_log_consts", since = "1.43.0")]
369    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
370
371    /// log<sub>10</sub>(e)
372    #[stable(feature = "rust1", since = "1.0.0")]
373    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
374
375    /// log<sub>10</sub>(2)
376    #[stable(feature = "extra_log_consts", since = "1.43.0")]
377    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
378
379    /// ln(2)
380    #[stable(feature = "rust1", since = "1.0.0")]
381    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
382
383    /// ln(10)
384    #[stable(feature = "rust1", since = "1.0.0")]
385    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
386}
387
388impl f32 {
389    /// The radix or base of the internal representation of `f32`.
390    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
391    pub const RADIX: u32 = 2;
392
393    /// Number of significant digits in base 2.
394    ///
395    /// Note that the size of the mantissa in the bitwise representation is one
396    /// smaller than this since the leading 1 is not stored explicitly.
397    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
398    pub const MANTISSA_DIGITS: u32 = 24;
399
400    /// Approximate number of significant digits in base 10.
401    ///
402    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
403    /// significant digits can be converted to `f32` and back without loss.
404    ///
405    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
406    ///
407    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
408    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
409    pub const DIGITS: u32 = 6;
410
411    /// [Machine epsilon] value for `f32`.
412    ///
413    /// This is the difference between `1.0` and the next larger representable number.
414    ///
415    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
416    ///
417    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
418    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
419    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
420    #[rustc_diagnostic_item = "f32_epsilon"]
421    pub const EPSILON: f32 = 1.19209290e-07_f32;
422
423    /// Smallest finite `f32` value.
424    ///
425    /// Equal to &minus;[`MAX`].
426    ///
427    /// [`MAX`]: f32::MAX
428    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
429    pub const MIN: f32 = -3.40282347e+38_f32;
430    /// Smallest positive normal `f32` value.
431    ///
432    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
433    ///
434    /// [`MIN_EXP`]: f32::MIN_EXP
435    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
436    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
437    /// Largest finite `f32` value.
438    ///
439    /// Equal to
440    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
441    ///
442    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
443    /// [`MAX_EXP`]: f32::MAX_EXP
444    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
445    pub const MAX: f32 = 3.40282347e+38_f32;
446
447    /// One greater than the minimum possible *normal* power of 2 exponent
448    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
449    ///
450    /// This corresponds to the exact minimum possible *normal* power of 2 exponent
451    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
452    /// In other words, all normal numbers representable by this type are
453    /// greater than or equal to 0.5&nbsp;×&nbsp;2<sup><i>MIN_EXP</i></sup>.
454    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
455    pub const MIN_EXP: i32 = -125;
456    /// One greater than the maximum possible power of 2 exponent
457    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
458    ///
459    /// This corresponds to the exact maximum possible power of 2 exponent
460    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
461    /// In other words, all numbers representable by this type are
462    /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
463    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
464    pub const MAX_EXP: i32 = 128;
465
466    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
467    ///
468    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
469    ///
470    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
471    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
472    pub const MIN_10_EXP: i32 = -37;
473    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
474    ///
475    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
476    ///
477    /// [`MAX`]: f32::MAX
478    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
479    pub const MAX_10_EXP: i32 = 38;
480
481    /// Not a Number (NaN).
482    ///
483    /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
484    /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
485    /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
486    /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
487    /// info.
488    ///
489    /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
490    /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
491    /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
492    /// The concrete bit pattern may change across Rust versions and target platforms.
493    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
494    #[rustc_diagnostic_item = "f32_nan"]
495    #[allow(clippy::eq_op)]
496    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
497    /// Infinity (∞).
498    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
499    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
500    /// Negative infinity (−∞).
501    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
502    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
503
504    /// Sign bit
505    pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
506
507    /// Exponent mask
508    pub(crate) const EXP_MASK: u32 = 0x7f80_0000;
509
510    /// Mantissa mask
511    pub(crate) const MAN_MASK: u32 = 0x007f_ffff;
512
513    /// Minimum representable positive value (min subnormal)
514    const TINY_BITS: u32 = 0x1;
515
516    /// Minimum representable negative value (min negative subnormal)
517    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
518
519    /// Returns `true` if this value is NaN.
520    ///
521    /// ```
522    /// let nan = f32::NAN;
523    /// let f = 7.0_f32;
524    ///
525    /// assert!(nan.is_nan());
526    /// assert!(!f.is_nan());
527    /// ```
528    #[must_use]
529    #[stable(feature = "rust1", since = "1.0.0")]
530    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
531    #[inline]
532    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
533    pub const fn is_nan(self) -> bool {
534        self != self
535    }
536
537    /// Returns `true` if this value is positive infinity or negative infinity, and
538    /// `false` otherwise.
539    ///
540    /// ```
541    /// let f = 7.0f32;
542    /// let inf = f32::INFINITY;
543    /// let neg_inf = f32::NEG_INFINITY;
544    /// let nan = f32::NAN;
545    ///
546    /// assert!(!f.is_infinite());
547    /// assert!(!nan.is_infinite());
548    ///
549    /// assert!(inf.is_infinite());
550    /// assert!(neg_inf.is_infinite());
551    /// ```
552    #[must_use]
553    #[stable(feature = "rust1", since = "1.0.0")]
554    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
555    #[inline]
556    pub const fn is_infinite(self) -> bool {
557        // Getting clever with transmutation can result in incorrect answers on some FPUs
558        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
559        // See https://github.com/rust-lang/rust/issues/72327
560        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
561    }
562
563    /// Returns `true` if this number is neither infinite nor NaN.
564    ///
565    /// ```
566    /// let f = 7.0f32;
567    /// let inf = f32::INFINITY;
568    /// let neg_inf = f32::NEG_INFINITY;
569    /// let nan = f32::NAN;
570    ///
571    /// assert!(f.is_finite());
572    ///
573    /// assert!(!nan.is_finite());
574    /// assert!(!inf.is_finite());
575    /// assert!(!neg_inf.is_finite());
576    /// ```
577    #[must_use]
578    #[stable(feature = "rust1", since = "1.0.0")]
579    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
580    #[inline]
581    pub const fn is_finite(self) -> bool {
582        // There's no need to handle NaN separately: if self is NaN,
583        // the comparison is not true, exactly as desired.
584        self.abs() < Self::INFINITY
585    }
586
587    /// Returns `true` if the number is [subnormal].
588    ///
589    /// ```
590    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
591    /// let max = f32::MAX;
592    /// let lower_than_min = 1.0e-40_f32;
593    /// let zero = 0.0_f32;
594    ///
595    /// assert!(!min.is_subnormal());
596    /// assert!(!max.is_subnormal());
597    ///
598    /// assert!(!zero.is_subnormal());
599    /// assert!(!f32::NAN.is_subnormal());
600    /// assert!(!f32::INFINITY.is_subnormal());
601    /// // Values between `0` and `min` are Subnormal.
602    /// assert!(lower_than_min.is_subnormal());
603    /// ```
604    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
605    #[must_use]
606    #[stable(feature = "is_subnormal", since = "1.53.0")]
607    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
608    #[inline]
609    pub const fn is_subnormal(self) -> bool {
610        matches!(self.classify(), FpCategory::Subnormal)
611    }
612
613    /// Returns `true` if the number is neither zero, infinite,
614    /// [subnormal], or NaN.
615    ///
616    /// ```
617    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
618    /// let max = f32::MAX;
619    /// let lower_than_min = 1.0e-40_f32;
620    /// let zero = 0.0_f32;
621    ///
622    /// assert!(min.is_normal());
623    /// assert!(max.is_normal());
624    ///
625    /// assert!(!zero.is_normal());
626    /// assert!(!f32::NAN.is_normal());
627    /// assert!(!f32::INFINITY.is_normal());
628    /// // Values between `0` and `min` are Subnormal.
629    /// assert!(!lower_than_min.is_normal());
630    /// ```
631    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
632    #[must_use]
633    #[stable(feature = "rust1", since = "1.0.0")]
634    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
635    #[inline]
636    pub const fn is_normal(self) -> bool {
637        matches!(self.classify(), FpCategory::Normal)
638    }
639
640    /// Returns the floating point category of the number. If only one property
641    /// is going to be tested, it is generally faster to use the specific
642    /// predicate instead.
643    ///
644    /// ```
645    /// use std::num::FpCategory;
646    ///
647    /// let num = 12.4_f32;
648    /// let inf = f32::INFINITY;
649    ///
650    /// assert_eq!(num.classify(), FpCategory::Normal);
651    /// assert_eq!(inf.classify(), FpCategory::Infinite);
652    /// ```
653    #[stable(feature = "rust1", since = "1.0.0")]
654    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
655    pub const fn classify(self) -> FpCategory {
656        // We used to have complicated logic here that avoids the simple bit-based tests to work
657        // around buggy codegen for x87 targets (see
658        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
659        // of our tests is able to find any difference between the complicated and the naive
660        // version, so now we are back to the naive version.
661        let b = self.to_bits();
662        match (b & Self::MAN_MASK, b & Self::EXP_MASK) {
663            (0, Self::EXP_MASK) => FpCategory::Infinite,
664            (_, Self::EXP_MASK) => FpCategory::Nan,
665            (0, 0) => FpCategory::Zero,
666            (_, 0) => FpCategory::Subnormal,
667            _ => FpCategory::Normal,
668        }
669    }
670
671    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
672    /// positive sign bit and positive infinity.
673    ///
674    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
675    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
676    /// conserved over arithmetic operations, the result of `is_sign_positive` on
677    /// a NaN might produce an unexpected or non-portable result. See the [specification
678    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
679    /// if you need fully portable behavior (will return `false` for all NaNs).
680    ///
681    /// ```
682    /// let f = 7.0_f32;
683    /// let g = -7.0_f32;
684    ///
685    /// assert!(f.is_sign_positive());
686    /// assert!(!g.is_sign_positive());
687    /// ```
688    #[must_use]
689    #[stable(feature = "rust1", since = "1.0.0")]
690    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
691    #[inline]
692    pub const fn is_sign_positive(self) -> bool {
693        !self.is_sign_negative()
694    }
695
696    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
697    /// negative sign bit and negative infinity.
698    ///
699    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
700    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
701    /// conserved over arithmetic operations, the result of `is_sign_negative` on
702    /// a NaN might produce an unexpected or non-portable result. See the [specification
703    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
704    /// if you need fully portable behavior (will return `false` for all NaNs).
705    ///
706    /// ```
707    /// let f = 7.0f32;
708    /// let g = -7.0f32;
709    ///
710    /// assert!(!f.is_sign_negative());
711    /// assert!(g.is_sign_negative());
712    /// ```
713    #[must_use]
714    #[stable(feature = "rust1", since = "1.0.0")]
715    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
716    #[inline]
717    pub const fn is_sign_negative(self) -> bool {
718        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
719        // applies to zeros and NaNs as well.
720        self.to_bits() & 0x8000_0000 != 0
721    }
722
723    /// Returns the least number greater than `self`.
724    ///
725    /// Let `TINY` be the smallest representable positive `f32`. Then,
726    ///  - if `self.is_nan()`, this returns `self`;
727    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
728    ///  - if `self` is `-TINY`, this returns -0.0;
729    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
730    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
731    ///  - otherwise the unique least value greater than `self` is returned.
732    ///
733    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
734    /// is finite `x == x.next_up().next_down()` also holds.
735    ///
736    /// ```rust
737    /// // f32::EPSILON is the difference between 1.0 and the next number up.
738    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
739    /// // But not for most numbers.
740    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
741    /// assert_eq!(16777216f32.next_up(), 16777218.0);
742    /// ```
743    ///
744    /// This operation corresponds to IEEE-754 `nextUp`.
745    ///
746    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
747    /// [`INFINITY`]: Self::INFINITY
748    /// [`MIN`]: Self::MIN
749    /// [`MAX`]: Self::MAX
750    #[inline]
751    #[doc(alias = "nextUp")]
752    #[stable(feature = "float_next_up_down", since = "1.86.0")]
753    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
754    pub const fn next_up(self) -> Self {
755        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
756        // denormals to zero. This is in general unsound and unsupported, but here
757        // we do our best to still produce the correct result on such targets.
758        let bits = self.to_bits();
759        if self.is_nan() || bits == Self::INFINITY.to_bits() {
760            return self;
761        }
762
763        let abs = bits & !Self::SIGN_MASK;
764        let next_bits = if abs == 0 {
765            Self::TINY_BITS
766        } else if bits == abs {
767            bits + 1
768        } else {
769            bits - 1
770        };
771        Self::from_bits(next_bits)
772    }
773
774    /// Returns the greatest number less than `self`.
775    ///
776    /// Let `TINY` be the smallest representable positive `f32`. Then,
777    ///  - if `self.is_nan()`, this returns `self`;
778    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
779    ///  - if `self` is `TINY`, this returns 0.0;
780    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
781    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
782    ///  - otherwise the unique greatest value less than `self` is returned.
783    ///
784    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
785    /// is finite `x == x.next_down().next_up()` also holds.
786    ///
787    /// ```rust
788    /// let x = 1.0f32;
789    /// // Clamp value into range [0, 1).
790    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
791    /// assert!(clamped < 1.0);
792    /// assert_eq!(clamped.next_up(), 1.0);
793    /// ```
794    ///
795    /// This operation corresponds to IEEE-754 `nextDown`.
796    ///
797    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
798    /// [`INFINITY`]: Self::INFINITY
799    /// [`MIN`]: Self::MIN
800    /// [`MAX`]: Self::MAX
801    #[inline]
802    #[doc(alias = "nextDown")]
803    #[stable(feature = "float_next_up_down", since = "1.86.0")]
804    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
805    pub const fn next_down(self) -> Self {
806        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
807        // denormals to zero. This is in general unsound and unsupported, but here
808        // we do our best to still produce the correct result on such targets.
809        let bits = self.to_bits();
810        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
811            return self;
812        }
813
814        let abs = bits & !Self::SIGN_MASK;
815        let next_bits = if abs == 0 {
816            Self::NEG_TINY_BITS
817        } else if bits == abs {
818            bits - 1
819        } else {
820            bits + 1
821        };
822        Self::from_bits(next_bits)
823    }
824
825    /// Takes the reciprocal (inverse) of a number, `1/x`.
826    ///
827    /// ```
828    /// let x = 2.0_f32;
829    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
830    ///
831    /// assert!(abs_difference <= f32::EPSILON);
832    /// ```
833    #[must_use = "this returns the result of the operation, without modifying the original"]
834    #[stable(feature = "rust1", since = "1.0.0")]
835    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
836    #[inline]
837    pub const fn recip(self) -> f32 {
838        1.0 / self
839    }
840
841    /// Converts radians to degrees.
842    ///
843    /// # Unspecified precision
844    ///
845    /// The precision of this function is non-deterministic. This means it varies by platform,
846    /// Rust version, and can even differ within the same execution from one invocation to the next.
847    ///
848    /// # Examples
849    ///
850    /// ```
851    /// let angle = std::f32::consts::PI;
852    ///
853    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
854    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
855    /// assert!(abs_difference <= f32::EPSILON);
856    /// ```
857    #[must_use = "this returns the result of the operation, \
858                  without modifying the original"]
859    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
860    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
861    #[inline]
862    pub const fn to_degrees(self) -> f32 {
863        // Use a literal to avoid double rounding, consts::PI is already rounded,
864        // and dividing would round again.
865        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
866        self * PIS_IN_180
867    }
868
869    /// Converts degrees to radians.
870    ///
871    /// # Unspecified precision
872    ///
873    /// The precision of this function is non-deterministic. This means it varies by platform,
874    /// Rust version, and can even differ within the same execution from one invocation to the next.
875    ///
876    /// # Examples
877    ///
878    /// ```
879    /// let angle = 180.0f32;
880    ///
881    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
882    ///
883    /// assert!(abs_difference <= f32::EPSILON);
884    /// ```
885    #[must_use = "this returns the result of the operation, \
886                  without modifying the original"]
887    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
888    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
889    #[inline]
890    pub const fn to_radians(self) -> f32 {
891        // The division here is correctly rounded with respect to the true value of π/180.
892        // Although π is irrational and already rounded, the double rounding happens
893        // to produce correct result for f32.
894        const RADS_PER_DEG: f32 = consts::PI / 180.0;
895        self * RADS_PER_DEG
896    }
897
898    /// Returns the maximum of the two numbers, ignoring NaN.
899    ///
900    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
901    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
902    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
903    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
904    /// non-deterministically.
905    ///
906    /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
907    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
908    /// follows the IEEE 754-2008 semantics for `maxNum`.
909    ///
910    /// ```
911    /// let x = 1.0f32;
912    /// let y = 2.0f32;
913    ///
914    /// assert_eq!(x.max(y), y);
915    /// assert_eq!(x.max(f32::NAN), x);
916    /// ```
917    #[must_use = "this returns the result of the comparison, without modifying either input"]
918    #[stable(feature = "rust1", since = "1.0.0")]
919    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
920    #[inline]
921    pub const fn max(self, other: f32) -> f32 {
922        intrinsics::maxnumf32(self, other)
923    }
924
925    /// Returns the minimum of the two numbers, ignoring NaN.
926    ///
927    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
928    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
929    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
930    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
931    /// non-deterministically.
932    ///
933    /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
934    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
935    /// follows the IEEE 754-2008 semantics for `minNum`.
936    ///
937    /// ```
938    /// let x = 1.0f32;
939    /// let y = 2.0f32;
940    ///
941    /// assert_eq!(x.min(y), x);
942    /// assert_eq!(x.min(f32::NAN), x);
943    /// ```
944    #[must_use = "this returns the result of the comparison, without modifying either input"]
945    #[stable(feature = "rust1", since = "1.0.0")]
946    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
947    #[inline]
948    pub const fn min(self, other: f32) -> f32 {
949        intrinsics::minnumf32(self, other)
950    }
951
952    /// Returns the maximum of the two numbers, propagating NaN.
953    ///
954    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
955    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
956    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
957    /// non-NaN inputs.
958    ///
959    /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
960    /// and which does not reliably order `-0.0` and `+0.0`.
961    ///
962    /// This follows the IEEE 754-2019 semantics for `maximum`.
963    ///
964    /// ```
965    /// #![feature(float_minimum_maximum)]
966    /// let x = 1.0f32;
967    /// let y = 2.0f32;
968    ///
969    /// assert_eq!(x.maximum(y), y);
970    /// assert!(x.maximum(f32::NAN).is_nan());
971    /// ```
972    #[must_use = "this returns the result of the comparison, without modifying either input"]
973    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
974    #[inline]
975    pub const fn maximum(self, other: f32) -> f32 {
976        intrinsics::maximumf32(self, other)
977    }
978
979    /// Returns the minimum of the two numbers, propagating NaN.
980    ///
981    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
982    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
983    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
984    /// non-NaN inputs.
985    ///
986    /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
987    /// and which does not reliably order `-0.0` and `+0.0`.
988    ///
989    /// This follows the IEEE 754-2019 semantics for `minimum`.
990    ///
991    /// ```
992    /// #![feature(float_minimum_maximum)]
993    /// let x = 1.0f32;
994    /// let y = 2.0f32;
995    ///
996    /// assert_eq!(x.minimum(y), x);
997    /// assert!(x.minimum(f32::NAN).is_nan());
998    /// ```
999    #[must_use = "this returns the result of the comparison, without modifying either input"]
1000    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1001    #[inline]
1002    pub const fn minimum(self, other: f32) -> f32 {
1003        intrinsics::minimumf32(self, other)
1004    }
1005
1006    /// Calculates the midpoint (average) between `self` and `rhs`.
1007    ///
1008    /// This returns NaN when *either* argument is NaN or if a combination of
1009    /// +inf and -inf is provided as arguments.
1010    ///
1011    /// # Examples
1012    ///
1013    /// ```
1014    /// assert_eq!(1f32.midpoint(4.0), 2.5);
1015    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1016    /// ```
1017    #[inline]
1018    #[doc(alias = "average")]
1019    #[stable(feature = "num_midpoint", since = "1.85.0")]
1020    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1021    pub const fn midpoint(self, other: f32) -> f32 {
1022        cfg_select! {
1023            // Allow faster implementation that have known good 64-bit float
1024            // implementations. Falling back to the branchy code on targets that don't
1025            // have 64-bit hardware floats or buggy implementations.
1026            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1027            any(
1028                target_arch = "x86_64",
1029                target_arch = "aarch64",
1030                all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1031                all(target_arch = "loongarch64", target_feature = "d"),
1032                all(target_arch = "arm", target_feature = "vfp2"),
1033                target_arch = "wasm32",
1034                target_arch = "wasm64",
1035            ) => {
1036                ((self as f64 + other as f64) / 2.0) as f32
1037            }
1038            _ => {
1039                const HI: f32 = f32::MAX / 2.;
1040
1041                let (a, b) = (self, other);
1042                let abs_a = a.abs();
1043                let abs_b = b.abs();
1044
1045                if abs_a <= HI && abs_b <= HI {
1046                    // Overflow is impossible
1047                    (a + b) / 2.
1048                } else {
1049                    (a / 2.) + (b / 2.)
1050                }
1051            }
1052        }
1053    }
1054
1055    /// Rounds toward zero and converts to any primitive integer type,
1056    /// assuming that the value is finite and fits in that type.
1057    ///
1058    /// ```
1059    /// let value = 4.6_f32;
1060    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1061    /// assert_eq!(rounded, 4);
1062    ///
1063    /// let value = -128.9_f32;
1064    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1065    /// assert_eq!(rounded, i8::MIN);
1066    /// ```
1067    ///
1068    /// # Safety
1069    ///
1070    /// The value must:
1071    ///
1072    /// * Not be `NaN`
1073    /// * Not be infinite
1074    /// * Be representable in the return type `Int`, after truncating off its fractional part
1075    #[must_use = "this returns the result of the operation, \
1076                  without modifying the original"]
1077    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1078    #[inline]
1079    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1080    where
1081        Self: FloatToInt<Int>,
1082    {
1083        // SAFETY: the caller must uphold the safety contract for
1084        // `FloatToInt::to_int_unchecked`.
1085        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1086    }
1087
1088    /// Raw transmutation to `u32`.
1089    ///
1090    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1091    ///
1092    /// See [`from_bits`](Self::from_bits) for some discussion of the
1093    /// portability of this operation (there are almost no issues).
1094    ///
1095    /// Note that this function is distinct from `as` casting, which attempts to
1096    /// preserve the *numeric* value, and not the bitwise value.
1097    ///
1098    /// # Examples
1099    ///
1100    /// ```
1101    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1102    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1103    ///
1104    /// ```
1105    #[must_use = "this returns the result of the operation, \
1106                  without modifying the original"]
1107    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1108    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1109    #[inline]
1110    #[allow(unnecessary_transmutes)]
1111    pub const fn to_bits(self) -> u32 {
1112        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1113        unsafe { mem::transmute(self) }
1114    }
1115
1116    /// Raw transmutation from `u32`.
1117    ///
1118    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1119    /// It turns out this is incredibly portable, for two reasons:
1120    ///
1121    /// * Floats and Ints have the same endianness on all supported platforms.
1122    /// * IEEE 754 very precisely specifies the bit layout of floats.
1123    ///
1124    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1125    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1126    /// (notably x86 and ARM) picked the interpretation that was ultimately
1127    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1128    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1129    ///
1130    /// Rather than trying to preserve signaling-ness cross-platform, this
1131    /// implementation favors preserving the exact bits. This means that
1132    /// any payloads encoded in NaNs will be preserved even if the result of
1133    /// this method is sent over the network from an x86 machine to a MIPS one.
1134    ///
1135    /// If the results of this method are only manipulated by the same
1136    /// architecture that produced them, then there is no portability concern.
1137    ///
1138    /// If the input isn't NaN, then there is no portability concern.
1139    ///
1140    /// If you don't care about signalingness (very likely), then there is no
1141    /// portability concern.
1142    ///
1143    /// Note that this function is distinct from `as` casting, which attempts to
1144    /// preserve the *numeric* value, and not the bitwise value.
1145    ///
1146    /// # Examples
1147    ///
1148    /// ```
1149    /// let v = f32::from_bits(0x41480000);
1150    /// assert_eq!(v, 12.5);
1151    /// ```
1152    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1153    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1154    #[must_use]
1155    #[inline]
1156    #[allow(unnecessary_transmutes)]
1157    pub const fn from_bits(v: u32) -> Self {
1158        // It turns out the safety issues with sNaN were overblown! Hooray!
1159        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1160        unsafe { mem::transmute(v) }
1161    }
1162
1163    /// Returns the memory representation of this floating point number as a byte array in
1164    /// big-endian (network) byte order.
1165    ///
1166    /// See [`from_bits`](Self::from_bits) for some discussion of the
1167    /// portability of this operation (there are almost no issues).
1168    ///
1169    /// # Examples
1170    ///
1171    /// ```
1172    /// let bytes = 12.5f32.to_be_bytes();
1173    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1174    /// ```
1175    #[must_use = "this returns the result of the operation, \
1176                  without modifying the original"]
1177    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1178    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1179    #[inline]
1180    pub const fn to_be_bytes(self) -> [u8; 4] {
1181        self.to_bits().to_be_bytes()
1182    }
1183
1184    /// Returns the memory representation of this floating point number as a byte array in
1185    /// little-endian byte order.
1186    ///
1187    /// See [`from_bits`](Self::from_bits) for some discussion of the
1188    /// portability of this operation (there are almost no issues).
1189    ///
1190    /// # Examples
1191    ///
1192    /// ```
1193    /// let bytes = 12.5f32.to_le_bytes();
1194    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1195    /// ```
1196    #[must_use = "this returns the result of the operation, \
1197                  without modifying the original"]
1198    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1199    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1200    #[inline]
1201    pub const fn to_le_bytes(self) -> [u8; 4] {
1202        self.to_bits().to_le_bytes()
1203    }
1204
1205    /// Returns the memory representation of this floating point number as a byte array in
1206    /// native byte order.
1207    ///
1208    /// As the target platform's native endianness is used, portable code
1209    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1210    ///
1211    /// [`to_be_bytes`]: f32::to_be_bytes
1212    /// [`to_le_bytes`]: f32::to_le_bytes
1213    ///
1214    /// See [`from_bits`](Self::from_bits) for some discussion of the
1215    /// portability of this operation (there are almost no issues).
1216    ///
1217    /// # Examples
1218    ///
1219    /// ```
1220    /// let bytes = 12.5f32.to_ne_bytes();
1221    /// assert_eq!(
1222    ///     bytes,
1223    ///     if cfg!(target_endian = "big") {
1224    ///         [0x41, 0x48, 0x00, 0x00]
1225    ///     } else {
1226    ///         [0x00, 0x00, 0x48, 0x41]
1227    ///     }
1228    /// );
1229    /// ```
1230    #[must_use = "this returns the result of the operation, \
1231                  without modifying the original"]
1232    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1233    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1234    #[inline]
1235    pub const fn to_ne_bytes(self) -> [u8; 4] {
1236        self.to_bits().to_ne_bytes()
1237    }
1238
1239    /// Creates a floating point value from its representation as a byte array in big endian.
1240    ///
1241    /// See [`from_bits`](Self::from_bits) for some discussion of the
1242    /// portability of this operation (there are almost no issues).
1243    ///
1244    /// # Examples
1245    ///
1246    /// ```
1247    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1248    /// assert_eq!(value, 12.5);
1249    /// ```
1250    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1251    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1252    #[must_use]
1253    #[inline]
1254    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1255        Self::from_bits(u32::from_be_bytes(bytes))
1256    }
1257
1258    /// Creates a floating point value from its representation as a byte array in little endian.
1259    ///
1260    /// See [`from_bits`](Self::from_bits) for some discussion of the
1261    /// portability of this operation (there are almost no issues).
1262    ///
1263    /// # Examples
1264    ///
1265    /// ```
1266    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1267    /// assert_eq!(value, 12.5);
1268    /// ```
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    #[must_use]
1272    #[inline]
1273    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1274        Self::from_bits(u32::from_le_bytes(bytes))
1275    }
1276
1277    /// Creates a floating point value from its representation as a byte array in native endian.
1278    ///
1279    /// As the target platform's native endianness is used, portable code
1280    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1281    /// appropriate instead.
1282    ///
1283    /// [`from_be_bytes`]: f32::from_be_bytes
1284    /// [`from_le_bytes`]: f32::from_le_bytes
1285    ///
1286    /// See [`from_bits`](Self::from_bits) for some discussion of the
1287    /// portability of this operation (there are almost no issues).
1288    ///
1289    /// # Examples
1290    ///
1291    /// ```
1292    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1293    ///     [0x41, 0x48, 0x00, 0x00]
1294    /// } else {
1295    ///     [0x00, 0x00, 0x48, 0x41]
1296    /// });
1297    /// assert_eq!(value, 12.5);
1298    /// ```
1299    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1300    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1301    #[must_use]
1302    #[inline]
1303    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1304        Self::from_bits(u32::from_ne_bytes(bytes))
1305    }
1306
1307    /// Returns the ordering between `self` and `other`.
1308    ///
1309    /// Unlike the standard partial comparison between floating point numbers,
1310    /// this comparison always produces an ordering in accordance to
1311    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1312    /// floating point standard. The values are ordered in the following sequence:
1313    ///
1314    /// - negative quiet NaN
1315    /// - negative signaling NaN
1316    /// - negative infinity
1317    /// - negative numbers
1318    /// - negative subnormal numbers
1319    /// - negative zero
1320    /// - positive zero
1321    /// - positive subnormal numbers
1322    /// - positive numbers
1323    /// - positive infinity
1324    /// - positive signaling NaN
1325    /// - positive quiet NaN.
1326    ///
1327    /// The ordering established by this function does not always agree with the
1328    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1329    /// they consider negative and positive zero equal, while `total_cmp`
1330    /// doesn't.
1331    ///
1332    /// The interpretation of the signaling NaN bit follows the definition in
1333    /// the IEEE 754 standard, which may not match the interpretation by some of
1334    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1335    ///
1336    /// # Example
1337    ///
1338    /// ```
1339    /// struct GoodBoy {
1340    ///     name: String,
1341    ///     weight: f32,
1342    /// }
1343    ///
1344    /// let mut bois = vec![
1345    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1346    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1347    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1348    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1349    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1350    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1351    /// ];
1352    ///
1353    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1354    ///
1355    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1356    /// if f32::NAN.is_sign_negative() {
1357    ///     assert!(bois.into_iter().map(|b| b.weight)
1358    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1359    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1360    /// } else {
1361    ///     assert!(bois.into_iter().map(|b| b.weight)
1362    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1363    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1364    /// }
1365    /// ```
1366    #[stable(feature = "total_cmp", since = "1.62.0")]
1367    #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1368    #[must_use]
1369    #[inline]
1370    pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1371        let mut left = self.to_bits() as i32;
1372        let mut right = other.to_bits() as i32;
1373
1374        // In case of negatives, flip all the bits except the sign
1375        // to achieve a similar layout as two's complement integers
1376        //
1377        // Why does this work? IEEE 754 floats consist of three fields:
1378        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1379        // fields as a whole have the property that their bitwise order is
1380        // equal to the numeric magnitude where the magnitude is defined.
1381        // The magnitude is not normally defined on NaN values, but
1382        // IEEE 754 totalOrder defines the NaN values also to follow the
1383        // bitwise order. This leads to order explained in the doc comment.
1384        // However, the representation of magnitude is the same for negative
1385        // and positive numbers – only the sign bit is different.
1386        // To easily compare the floats as signed integers, we need to
1387        // flip the exponent and mantissa bits in case of negative numbers.
1388        // We effectively convert the numbers to "two's complement" form.
1389        //
1390        // To do the flipping, we construct a mask and XOR against it.
1391        // We branchlessly calculate an "all-ones except for the sign bit"
1392        // mask from negative-signed values: right shifting sign-extends
1393        // the integer, so we "fill" the mask with sign bits, and then
1394        // convert to unsigned to push one more zero bit.
1395        // On positive values, the mask is all zeros, so it's a no-op.
1396        left ^= (((left >> 31) as u32) >> 1) as i32;
1397        right ^= (((right >> 31) as u32) >> 1) as i32;
1398
1399        left.cmp(&right)
1400    }
1401
1402    /// Restrict a value to a certain interval unless it is NaN.
1403    ///
1404    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1405    /// less than `min`. Otherwise this returns `self`.
1406    ///
1407    /// Note that this function returns NaN if the initial value was NaN as
1408    /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1409    /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1410    ///
1411    /// # Panics
1412    ///
1413    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1414    ///
1415    /// # Examples
1416    ///
1417    /// ```
1418    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1419    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1420    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1421    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1422    ///
1423    /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1424    /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1425    /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1426    /// // This is definitely a negative zero.
1427    /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1428    /// ```
1429    #[must_use = "method returns a new number and does not mutate the original value"]
1430    #[stable(feature = "clamp", since = "1.50.0")]
1431    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1432    #[inline]
1433    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1434        const_assert!(
1435            min <= max,
1436            "min > max, or either was NaN",
1437            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1438            min: f32,
1439            max: f32,
1440        );
1441
1442        if self < min {
1443            self = min;
1444        }
1445        if self > max {
1446            self = max;
1447        }
1448        self
1449    }
1450
1451    /// Clamps this number to a symmetric range centered around zero.
1452    ///
1453    /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1454    ///
1455    /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1456    /// explicit about the intent.
1457    ///
1458    /// # Panics
1459    ///
1460    /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1461    ///
1462    /// # Examples
1463    ///
1464    /// ```
1465    /// #![feature(clamp_magnitude)]
1466    /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1467    /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1468    /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1469    /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1470    /// ```
1471    #[must_use = "this returns the clamped value and does not modify the original"]
1472    #[unstable(feature = "clamp_magnitude", issue = "148519")]
1473    #[inline]
1474    pub fn clamp_magnitude(self, limit: f32) -> f32 {
1475        assert!(limit >= 0.0, "limit must be non-negative");
1476        let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1477        self.clamp(-limit, limit)
1478    }
1479
1480    /// Computes the absolute value of `self`.
1481    ///
1482    /// This function always returns the precise result.
1483    ///
1484    /// # Examples
1485    ///
1486    /// ```
1487    /// let x = 3.5_f32;
1488    /// let y = -3.5_f32;
1489    ///
1490    /// assert_eq!(x.abs(), x);
1491    /// assert_eq!(y.abs(), -y);
1492    ///
1493    /// assert!(f32::NAN.abs().is_nan());
1494    /// ```
1495    #[must_use = "method returns a new number and does not mutate the original value"]
1496    #[stable(feature = "rust1", since = "1.0.0")]
1497    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1498    #[inline]
1499    pub const fn abs(self) -> f32 {
1500        intrinsics::fabsf32(self)
1501    }
1502
1503    /// Returns a number that represents the sign of `self`.
1504    ///
1505    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1506    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1507    /// - NaN if the number is NaN
1508    ///
1509    /// # Examples
1510    ///
1511    /// ```
1512    /// let f = 3.5_f32;
1513    ///
1514    /// assert_eq!(f.signum(), 1.0);
1515    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1516    ///
1517    /// assert!(f32::NAN.signum().is_nan());
1518    /// ```
1519    #[must_use = "method returns a new number and does not mutate the original value"]
1520    #[stable(feature = "rust1", since = "1.0.0")]
1521    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1522    #[inline]
1523    pub const fn signum(self) -> f32 {
1524        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1525    }
1526
1527    /// Returns a number composed of the magnitude of `self` and the sign of
1528    /// `sign`.
1529    ///
1530    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1531    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1532    /// returned.
1533    ///
1534    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1535    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1536    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1537    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1538    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1539    /// info.
1540    ///
1541    /// # Examples
1542    ///
1543    /// ```
1544    /// let f = 3.5_f32;
1545    ///
1546    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1547    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1548    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1549    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1550    ///
1551    /// assert!(f32::NAN.copysign(1.0).is_nan());
1552    /// ```
1553    #[must_use = "method returns a new number and does not mutate the original value"]
1554    #[inline]
1555    #[stable(feature = "copysign", since = "1.35.0")]
1556    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1557    pub const fn copysign(self, sign: f32) -> f32 {
1558        intrinsics::copysignf32(self, sign)
1559    }
1560
1561    /// Float addition that allows optimizations based on algebraic rules.
1562    ///
1563    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1564    #[must_use = "method returns a new number and does not mutate the original value"]
1565    #[unstable(feature = "float_algebraic", issue = "136469")]
1566    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1567    #[inline]
1568    pub const fn algebraic_add(self, rhs: f32) -> f32 {
1569        intrinsics::fadd_algebraic(self, rhs)
1570    }
1571
1572    /// Float subtraction that allows optimizations based on algebraic rules.
1573    ///
1574    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1575    #[must_use = "method returns a new number and does not mutate the original value"]
1576    #[unstable(feature = "float_algebraic", issue = "136469")]
1577    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1578    #[inline]
1579    pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1580        intrinsics::fsub_algebraic(self, rhs)
1581    }
1582
1583    /// Float multiplication that allows optimizations based on algebraic rules.
1584    ///
1585    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1586    #[must_use = "method returns a new number and does not mutate the original value"]
1587    #[unstable(feature = "float_algebraic", issue = "136469")]
1588    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1589    #[inline]
1590    pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1591        intrinsics::fmul_algebraic(self, rhs)
1592    }
1593
1594    /// Float division that allows optimizations based on algebraic rules.
1595    ///
1596    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1597    #[must_use = "method returns a new number and does not mutate the original value"]
1598    #[unstable(feature = "float_algebraic", issue = "136469")]
1599    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1600    #[inline]
1601    pub const fn algebraic_div(self, rhs: f32) -> f32 {
1602        intrinsics::fdiv_algebraic(self, rhs)
1603    }
1604
1605    /// Float remainder that allows optimizations based on algebraic rules.
1606    ///
1607    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1608    #[must_use = "method returns a new number and does not mutate the original value"]
1609    #[unstable(feature = "float_algebraic", issue = "136469")]
1610    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1611    #[inline]
1612    pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1613        intrinsics::frem_algebraic(self, rhs)
1614    }
1615}
1616
1617/// Experimental implementations of floating point functions in `core`.
1618///
1619/// _The standalone functions in this module are for testing only.
1620/// They will be stabilized as inherent methods._
1621#[unstable(feature = "core_float_math", issue = "137578")]
1622pub mod math {
1623    use crate::intrinsics;
1624    use crate::num::libm;
1625
1626    /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1627    ///
1628    /// # Examples
1629    ///
1630    /// ```
1631    /// #![feature(core_float_math)]
1632    ///
1633    /// use core::f32;
1634    ///
1635    /// let f = 3.7_f32;
1636    /// let g = 3.0_f32;
1637    /// let h = -3.7_f32;
1638    ///
1639    /// assert_eq!(f32::math::floor(f), 3.0);
1640    /// assert_eq!(f32::math::floor(g), 3.0);
1641    /// assert_eq!(f32::math::floor(h), -4.0);
1642    /// ```
1643    ///
1644    /// _This standalone function is for testing only.
1645    /// It will be stabilized as an inherent method._
1646    ///
1647    /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1648    #[inline]
1649    #[unstable(feature = "core_float_math", issue = "137578")]
1650    #[must_use = "method returns a new number and does not mutate the original value"]
1651    pub const fn floor(x: f32) -> f32 {
1652        intrinsics::floorf32(x)
1653    }
1654
1655    /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1656    ///
1657    /// # Examples
1658    ///
1659    /// ```
1660    /// #![feature(core_float_math)]
1661    ///
1662    /// use core::f32;
1663    ///
1664    /// let f = 3.01_f32;
1665    /// let g = 4.0_f32;
1666    ///
1667    /// assert_eq!(f32::math::ceil(f), 4.0);
1668    /// assert_eq!(f32::math::ceil(g), 4.0);
1669    /// ```
1670    ///
1671    /// _This standalone function is for testing only.
1672    /// It will be stabilized as an inherent method._
1673    ///
1674    /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1675    #[inline]
1676    #[doc(alias = "ceiling")]
1677    #[must_use = "method returns a new number and does not mutate the original value"]
1678    #[unstable(feature = "core_float_math", issue = "137578")]
1679    pub const fn ceil(x: f32) -> f32 {
1680        intrinsics::ceilf32(x)
1681    }
1682
1683    /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1684    ///
1685    /// # Examples
1686    ///
1687    /// ```
1688    /// #![feature(core_float_math)]
1689    ///
1690    /// use core::f32;
1691    ///
1692    /// let f = 3.3_f32;
1693    /// let g = -3.3_f32;
1694    /// let h = -3.7_f32;
1695    /// let i = 3.5_f32;
1696    /// let j = 4.5_f32;
1697    ///
1698    /// assert_eq!(f32::math::round(f), 3.0);
1699    /// assert_eq!(f32::math::round(g), -3.0);
1700    /// assert_eq!(f32::math::round(h), -4.0);
1701    /// assert_eq!(f32::math::round(i), 4.0);
1702    /// assert_eq!(f32::math::round(j), 5.0);
1703    /// ```
1704    ///
1705    /// _This standalone function is for testing only.
1706    /// It will be stabilized as an inherent method._
1707    ///
1708    /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1709    #[inline]
1710    #[unstable(feature = "core_float_math", issue = "137578")]
1711    #[must_use = "method returns a new number and does not mutate the original value"]
1712    pub const fn round(x: f32) -> f32 {
1713        intrinsics::roundf32(x)
1714    }
1715
1716    /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1717    /// details.
1718    ///
1719    /// # Examples
1720    ///
1721    /// ```
1722    /// #![feature(core_float_math)]
1723    ///
1724    /// use core::f32;
1725    ///
1726    /// let f = 3.3_f32;
1727    /// let g = -3.3_f32;
1728    /// let h = 3.5_f32;
1729    /// let i = 4.5_f32;
1730    ///
1731    /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1732    /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1733    /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1734    /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1735    /// ```
1736    ///
1737    /// _This standalone function is for testing only.
1738    /// It will be stabilized as an inherent method._
1739    ///
1740    /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1741    #[inline]
1742    #[unstable(feature = "core_float_math", issue = "137578")]
1743    #[must_use = "method returns a new number and does not mutate the original value"]
1744    pub const fn round_ties_even(x: f32) -> f32 {
1745        intrinsics::round_ties_even_f32(x)
1746    }
1747
1748    /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1749    ///
1750    /// # Examples
1751    ///
1752    /// ```
1753    /// #![feature(core_float_math)]
1754    ///
1755    /// use core::f32;
1756    ///
1757    /// let f = 3.7_f32;
1758    /// let g = 3.0_f32;
1759    /// let h = -3.7_f32;
1760    ///
1761    /// assert_eq!(f32::math::trunc(f), 3.0);
1762    /// assert_eq!(f32::math::trunc(g), 3.0);
1763    /// assert_eq!(f32::math::trunc(h), -3.0);
1764    /// ```
1765    ///
1766    /// _This standalone function is for testing only.
1767    /// It will be stabilized as an inherent method._
1768    ///
1769    /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1770    #[inline]
1771    #[doc(alias = "truncate")]
1772    #[must_use = "method returns a new number and does not mutate the original value"]
1773    #[unstable(feature = "core_float_math", issue = "137578")]
1774    pub const fn trunc(x: f32) -> f32 {
1775        intrinsics::truncf32(x)
1776    }
1777
1778    /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1779    ///
1780    /// # Examples
1781    ///
1782    /// ```
1783    /// #![feature(core_float_math)]
1784    ///
1785    /// use core::f32;
1786    ///
1787    /// let x = 3.6_f32;
1788    /// let y = -3.6_f32;
1789    /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1790    /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1791    ///
1792    /// assert!(abs_difference_x <= f32::EPSILON);
1793    /// assert!(abs_difference_y <= f32::EPSILON);
1794    /// ```
1795    ///
1796    /// _This standalone function is for testing only.
1797    /// It will be stabilized as an inherent method._
1798    ///
1799    /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1800    #[inline]
1801    #[unstable(feature = "core_float_math", issue = "137578")]
1802    #[must_use = "method returns a new number and does not mutate the original value"]
1803    pub const fn fract(x: f32) -> f32 {
1804        x - trunc(x)
1805    }
1806
1807    /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1808    ///
1809    /// # Examples
1810    ///
1811    /// ```
1812    /// #![feature(core_float_math)]
1813    ///
1814    /// # // FIXME(#140515): mingw has an incorrect fma
1815    /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1816    /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1817    /// use core::f32;
1818    ///
1819    /// let m = 10.0_f32;
1820    /// let x = 4.0_f32;
1821    /// let b = 60.0_f32;
1822    ///
1823    /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1824    /// assert_eq!(m * x + b, 100.0);
1825    ///
1826    /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1827    /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1828    /// let minus_one = -1.0_f32;
1829    ///
1830    /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1831    /// assert_eq!(
1832    ///     f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1833    ///     -f32::EPSILON * f32::EPSILON
1834    /// );
1835    /// // Different rounding with the non-fused multiply and add.
1836    /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1837    /// # }
1838    /// ```
1839    ///
1840    /// _This standalone function is for testing only.
1841    /// It will be stabilized as an inherent method._
1842    ///
1843    /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1844    #[inline]
1845    #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1846    #[must_use = "method returns a new number and does not mutate the original value"]
1847    #[unstable(feature = "core_float_math", issue = "137578")]
1848    #[rustc_const_unstable(feature = "const_mul_add", issue = "146724")]
1849    pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1850        intrinsics::fmaf32(x, y, z)
1851    }
1852
1853    /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1854    ///
1855    /// # Examples
1856    ///
1857    /// ```
1858    /// #![feature(core_float_math)]
1859    ///
1860    /// use core::f32;
1861    ///
1862    /// let a: f32 = 7.0;
1863    /// let b = 4.0;
1864    /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
1865    /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
1866    /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
1867    /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
1868    /// ```
1869    ///
1870    /// _This standalone function is for testing only.
1871    /// It will be stabilized as an inherent method._
1872    ///
1873    /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
1874    #[inline]
1875    #[unstable(feature = "core_float_math", issue = "137578")]
1876    #[must_use = "method returns a new number and does not mutate the original value"]
1877    pub fn div_euclid(x: f32, rhs: f32) -> f32 {
1878        let q = trunc(x / rhs);
1879        if x % rhs < 0.0 {
1880            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
1881        }
1882        q
1883    }
1884
1885    /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
1886    ///
1887    /// # Examples
1888    ///
1889    /// ```
1890    /// #![feature(core_float_math)]
1891    ///
1892    /// use core::f32;
1893    ///
1894    /// let a: f32 = 7.0;
1895    /// let b = 4.0;
1896    /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
1897    /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
1898    /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
1899    /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
1900    /// // limitation due to round-off error
1901    /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
1902    /// ```
1903    ///
1904    /// _This standalone function is for testing only.
1905    /// It will be stabilized as an inherent method._
1906    ///
1907    /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
1908    #[inline]
1909    #[doc(alias = "modulo", alias = "mod")]
1910    #[unstable(feature = "core_float_math", issue = "137578")]
1911    #[must_use = "method returns a new number and does not mutate the original value"]
1912    pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
1913        let r = x % rhs;
1914        if r < 0.0 { r + rhs.abs() } else { r }
1915    }
1916
1917    /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
1918    ///
1919    /// # Examples
1920    ///
1921    /// ```
1922    /// #![feature(core_float_math)]
1923    ///
1924    /// use core::f32;
1925    ///
1926    /// let x = 2.0_f32;
1927    /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
1928    /// assert!(abs_difference <= 1e-5);
1929    ///
1930    /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
1931    /// ```
1932    ///
1933    /// _This standalone function is for testing only.
1934    /// It will be stabilized as an inherent method._
1935    ///
1936    /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
1937    #[inline]
1938    #[must_use = "method returns a new number and does not mutate the original value"]
1939    #[unstable(feature = "core_float_math", issue = "137578")]
1940    pub fn powi(x: f32, n: i32) -> f32 {
1941        intrinsics::powif32(x, n)
1942    }
1943
1944    /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
1945    ///
1946    /// # Examples
1947    ///
1948    /// ```
1949    /// #![feature(core_float_math)]
1950    ///
1951    /// use core::f32;
1952    ///
1953    /// let positive = 4.0_f32;
1954    /// let negative = -4.0_f32;
1955    /// let negative_zero = -0.0_f32;
1956    ///
1957    /// assert_eq!(f32::math::sqrt(positive), 2.0);
1958    /// assert!(f32::math::sqrt(negative).is_nan());
1959    /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
1960    /// ```
1961    ///
1962    /// _This standalone function is for testing only.
1963    /// It will be stabilized as an inherent method._
1964    ///
1965    /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
1966    #[inline]
1967    #[doc(alias = "squareRoot")]
1968    #[unstable(feature = "core_float_math", issue = "137578")]
1969    #[must_use = "method returns a new number and does not mutate the original value"]
1970    pub fn sqrt(x: f32) -> f32 {
1971        intrinsics::sqrtf32(x)
1972    }
1973
1974    /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
1975    ///
1976    /// # Examples
1977    ///
1978    /// ```
1979    /// #![feature(core_float_math)]
1980    ///
1981    /// use core::f32;
1982    ///
1983    /// let x = 3.0f32;
1984    /// let y = -3.0f32;
1985    ///
1986    /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
1987    /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
1988    ///
1989    /// assert!(abs_difference_x <= 1e-6);
1990    /// assert!(abs_difference_y <= 1e-6);
1991    /// ```
1992    ///
1993    /// _This standalone function is for testing only.
1994    /// It will be stabilized as an inherent method._
1995    ///
1996    /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
1997    #[inline]
1998    #[stable(feature = "rust1", since = "1.0.0")]
1999    #[deprecated(
2000        since = "1.10.0",
2001        note = "you probably meant `(self - other).abs()`: \
2002            this operation is `(self - other).max(0.0)` \
2003            except that `abs_sub` also propagates NaNs (also \
2004            known as `fdimf` in C). If you truly need the positive \
2005            difference, consider using that expression or the C function \
2006            `fdimf`, depending on how you wish to handle NaN (please consider \
2007            filing an issue describing your use-case too)."
2008    )]
2009    #[must_use = "method returns a new number and does not mutate the original value"]
2010    pub fn abs_sub(x: f32, other: f32) -> f32 {
2011        libm::fdimf(x, other)
2012    }
2013
2014    /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2015    ///
2016    /// # Unspecified precision
2017    ///
2018    /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2019    /// can even differ within the same execution from one invocation to the next.
2020    /// This function currently corresponds to the `cbrtf` from libc on Unix
2021    /// and Windows. Note that this might change in the future.
2022    ///
2023    /// # Examples
2024    ///
2025    /// ```
2026    /// #![feature(core_float_math)]
2027    ///
2028    /// use core::f32;
2029    ///
2030    /// let x = 8.0f32;
2031    ///
2032    /// // x^(1/3) - 2 == 0
2033    /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2034    ///
2035    /// assert!(abs_difference <= 1e-6);
2036    /// ```
2037    ///
2038    /// _This standalone function is for testing only.
2039    /// It will be stabilized as an inherent method._
2040    ///
2041    /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2042    #[inline]
2043    #[must_use = "method returns a new number and does not mutate the original value"]
2044    #[unstable(feature = "core_float_math", issue = "137578")]
2045    pub fn cbrt(x: f32) -> f32 {
2046        libm::cbrtf(x)
2047    }
2048}