fmod, fmodf, fmodl − floating-point remainder function
fmod(double x, double y);
float fmodf(float x, float y);
long double fmodl(long double x, long double y);
Link with −lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_BSD_SOURCE || _SVID_SOURCE ||
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
The fmod() function computes the floating-point remainder of dividing x by y. The return value is x − n * y, where n is the quotient of x / y, rounded toward zero to an integer.
On success, these functions return the value x − n*y, for some integer n, such that the returned value has the same sign as x and a magnitude less than the magnitude of y.
If x or y is a NaN, a NaN is returned.
If x is an infinity, a domain error occurs, and a NaN is returned.
If y is zero, a domain error occurs, and a NaN is returned.
If x is +0 (−0), and y is not zero, +0 (−0) is returned.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
errors can occur:
Domain error: x is an infinity
errno is set to EDOM (but see BUGS). An invalid floating-point exception (FE_INVALID) is raised.
Domain error: y is zero
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).
C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89.
Before version 2.10, the glibc implementation did not set errno to EDOM when a domain error occurred for an infinite x.
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