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 (seefeature_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 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 (seefenv(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 Seemath_error(7)for information on how to determine whether an error ATTRIBUTES For an explanation of the terms used in this section, seeattributes(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 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 ALSOdiv(3),fmod(3),remquo(3)COLOPHON This page is part of release 4.04 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/. 2015-04-19REMAINDER(3)