remainder(3) Library Functions Manual remainder(3)

drem, dremf, dreml, remainder, remainderf, remainderl - floating-point remainder function

Math library (libm, -lm)

#include <math.h>
double remainder(double x, double y);
float remainderf(float x, float y);
long double remainderl(long double x, long double y);
/* Obsolete synonyms */
[[deprecated]] double drem(double x, double y);
[[deprecated]] float dremf(float x, float y);
[[deprecated]] long double dreml(long double x, long double y);
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 <= 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

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.

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.

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

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.
errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.

For an explanation of the terms used in this section, see attributes(7).

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

C11, POSIX.1-2008.
None.

C99, POSIX.1-2001.
4.3BSD.
Tru64, glibc2.

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.

The call "remainder(29.0, 3.0)" returns -1.

div(3), fmod(3), remquo(3)

2023-10-31 Linux man-pages 6.06