NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | BUGS | EXAMPLE | SEE ALSO | COLOPHON

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

NAME         top

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

SYNOPSIS         top

       #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         top

       The remainder() function computes 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         top

       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         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 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.

CONFORMING TO         top

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

       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         top

       The call

           remainder(nan(""), 0);

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

EXAMPLE         top

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 3.70 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       http://www.kernel.org/doc/man-pages/.

                                 2010-09-20                     REMAINDER(3)