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():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       remainderf(), remainderl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
       drem(), dremf(), dreml():
           /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 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).

       allbox;  lbw26  lb  lb  l  l  l.   Interface Attribute Value T{ drem(),
       dremf(), dreml(),
       remainder(), remainderf(),
       remainderl() T}   Thread safety  MT-Safe

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
       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.  errno was not set

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 4.16 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
       https://www.kernel.org/doc/man-pages/.



                                  2017-09-15                      REMAINDER(3)