dremf(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).

   ┌───────────────────────────┬───────────────┬─────────┐
   │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

   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 4.09 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/.

                              2016-12-12                      REMAINDER(3)

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