NAME

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

SYNOPSIS

       #include <math.h>

       /* The C99 versions */
       double remainder(double x, double y);
       float remainderf(float x, float y);
       long double remainderl(long double x, long double y);

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

       Link with -lm.

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

       remainder():
           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED ||
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99
       remainderf(), remainderl():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99
       drem(), dremf(), dreml():
           _SVID_SOURCE || _BSD_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
              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(),  │ Thread safety │ MT-Safe │
       │remainder(), remainderf(), │               │         │
       │remainderl()               │               │         │
       └───────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       The functions remainder(), remainderf(),  and  remainderl()  are  specified  in  C99,  POSIX.1-2001,  and
       POSIX.1-2008.

       The function drem() is from 4.3BSD.  The float and long double variants dremf() and dreml() exist on some
       systems, such as Tru64 and glibc2.  Avoid the use of these functions in favor of remainder() etc.

BUGS

       The call

           remainder(nan(""), 0);

       returns a NaN, as expected, but wrongly causes a domain error; it should yield a silent NaN.

EXAMPLE

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

SEE ALSO

       div(3), fmod(3), remquo(3)

COLOPHON

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       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       http://www.kernel.org/doc/man-pages/.

                                                   2015-04-19                                       REMAINDER(3)