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



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
       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
       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.

CONFORMING TO
       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
       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
       This page is part of release 3.74 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)