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Y0(3)                         Linux Programmer's Manual                         Y0(3)

NAME         top

       y0, y0f, y0l, y1, y1f, y1l, yn, ynf, ynl - Bessel functions of the second kind

SYNOPSIS         top

       #include <math.h>

       double y0(double x);
       double y1(double x);
       double yn(int n, double x);

       float y0f(float x);
       float y1f(float x);
       float ynf(int n, float x);

       long double y0l(long double x);
       long double y1l(long double x);
       long double ynl(int n, long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       y0(), y1(), yn():
           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE
       y0f(), y0l(), y1f(), y1l(), ynf(), ynl():
           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 600

DESCRIPTION         top

       The y0() and y1() functions return Bessel functions of x of the second kind of
       orders 0 and 1, respectively.  The yn() function returns the Bessel function
       of x of the second kind of order n.

       The value of x must be positive.

       The y0f() etc. and y0l() etc. functions are versions that take and return
       float and long double values, respectively.

RETURN VALUE         top

       On success, these functions return the appropriate Bessel value of the second
       kind for x.

       If x is a NaN, a NaN is returned.

       If x is negative, a domain error occurs, and the functions return -HUGE_VAL,
       -HUGE_VALF, or -HUGE_VALL, respectively.  (POSIX.1-2001 also allows a NaN
       return for this case.)

       If x is 0.0, a pole error occurs, and the functions return -HUGE_VAL,
       -HUGE_VALF, or -HUGE_VALL, respectively.

       If the result underflows, a range error occurs, and the functions return 0.0

       If the result overflows, a range error occurs, and the functions return
       -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively.  (POSIX.1-2001 also allows
       a 0.0 return for this case.)

ERRORS         top

       See math_error(7) for information on how to determine whether an error has
       occurred when calling these functions.

       The following errors can occur:

       Domain error: x is negative
              errno is set to EDOM.  An invalid floating-point exception (FE_INVALID)
              is raised.

       Pole error: x is 0.0
              errno is set to ERANGE (but see BUGS).  No FE_DIVBYZERO exception is
              returned by fetestexcept(3) for this case.

       Range error: result underflow
              errno is set to ERANGE.  No FE_UNDERFLOW exception is returned by
              fetestexcept(3) for this case.

       Range error: result overflow
              errno is not set for this case.  An overflow floating-point exception
              (FE_OVERFLOW) is raised.

CONFORMING TO         top

       The functions returning double conform to SVr4, 4.3BSD, POSIX.1-2001.  The
       others are nonstandard functions that also exist on the BSDs.

BUGS         top

       On a pole error, these functions set errno to EDOM, instead of ERANGE as
       POSIX.1-2004 requires.

       In glibc version 2.3.2 and earlier, these functions do not raise an invalid
       floating-point exception (FE_INVALID) when a domain error occurs.

SEE ALSO         top

       j0(3)

COLOPHON         top

       This page is part of release 3.32 of the Linux man-pages project.  A
       description of the project, and information about reporting bugs, can be found
       at http://www.kernel.org/doc/man-pages/.

                                      2008-08-10                                Y0(3)

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