remainder(3) — Linux manual page


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

           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       remainderf(), remainderl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       drem(), dremf(), dreml():
           /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       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

       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
              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         top

       For an explanation of the terms used in this section, see

       │Interface                             Attribute     Value   │
       │drem(), dremf(), dreml(),             │ Thread safety │ MT-Safe │
       │remainder(), remainderf(),            │               │         │
       │remainderl()                          │               │         │

CONFORMING TO         top

       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         top

       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

       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.

EXAMPLES         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 5.13 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

                               2021-03-22                   REMAINDER(3)

Pages that refer to this page: div(3)fma(3)fmod(3)remquo(3)