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  4.15  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)