NAME  SYNOPSIS  DESCRIPTION  RETURN VALUE  ERRORS  CONFORMING TO  BUGS  EXAMPLE  SEE ALSO  COLOPHON 

REMAINDER(3) Linux Programmer's Manual REMAINDER(3)
drem, dremf, dreml, remainder, remainderf, remainderl  floating point remainder function
#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(): _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
The remainder() function computes the remainder of dividing x by y. The return value is xn*y, where n is the value x / y, rounded to the nearest integer. If the absolute value of xn*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.
On success, these functions return the floatingpoint remainder, xn*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.
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 An invalid floatingpoint 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 floatingpoint exception (FE_INVALID) is raised.
The functions remainder(), remainderf(), and remainderl() are specified in C99 and POSIX.12001. 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.
The call remainder(nan(""), 0); returns a NaN, as expected, but wrongly causes a domain error; it should yield a silent NaN.
The call "remainder(29.0, 3.0)" returns 1.
div(3), fmod(3), remquo(3)
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20100920 REMAINDER(3)
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