remainder(3)               Library Functions Manual               remainder(3)

NAME
       drem, dremf, dreml, remainder, remainderf, remainderl - floating-point
       remainder function

LIBRARY
       Math library (libm, -lm)

SYNOPSIS
       #include <math.h>

       double remainder(double x, double y);
       float remainderf(float x, float y);
       long double remainderl(long double x, long double y);

       /* Obsolete synonyms */
       [[deprecated]] double drem(double x, double y);
       [[deprecated]] float dremf(float x, float y);
       [[deprecated]] long double dreml(long double x, long double y);

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

       remainder():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       remainderf(), remainderl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       drem(), dremf(), dreml():
           /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION
       These functions compute the remainder of dividing x by y.  The return
       value is x-n*y, where n is the value x / y, rounded to the nearest
       integer.  If the absolute value of x-n*y is 0.5, n is chosen to be
       even.

       These functions are unaffected by the current rounding mode (see
       fenv(3)).

       The drem() function does precisely the same thing.

RETURN VALUE
       On success, these functions return the floating-point remainder, x-n*y.
       If the return value is 0, it has the sign of x.

       If x or y is a NaN, a NaN is returned.

       If x is an infinity, and y is not a NaN, a domain error occurs, and a
       NaN is returned.

       If y is zero, and x is not a NaN, a domain error occurs, and a NaN is
       returned.

ERRORS
       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 an infinity and y is not a NaN
              errno is set to EDOM (but see BUGS).  An invalid floating-point
              exception (FE_INVALID) is raised.

              These functions do not set errno for this case.

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

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |drem (), dremf (), dreml (), remainder (),  | Thread safety | MT-Safe |
       |remainderf (), remainderl ()                |               |         |
       +--------------------------------------------+---------------+---------+
STANDARDS
       remainder()
       remainderf()
       remainderl()
              C11, POSIX.1-2008.

       drem()
       dremf()
       dreml()
              None.

HISTORY
       remainder()
       remainderf()
       remainderl()
              C99, POSIX.1-2001.

       drem() 4.3BSD.

       dremf()
       dreml()
              Tru64, glibc2.

BUGS
       Before glibc 2.15, the call

           remainder(nan(""), 0);

       returned a NaN, as expected, but wrongly caused a domain error.  Since
       glibc 2.15, a silent NaN (i.e., no domain error) is returned.

       Before glibc 2.15, errno was not set to EDOM for the domain error that
       occurs when x is an infinity and y is not a NaN.

EXAMPLES
       The call "remainder(29.0, 3.0)" returns -1.

SEE ALSO
       div(3), fmod(3), remquo(3)

Linux man-pages 6.7               2023-10-31                      remainder(3)