The fmod() function returns the floating-point remainder of the division of x by y.

The fmod() function returns the value x - i * y, for some integer i such that, if y is non-zero, the result has the same sign as x and magnitude less than the magnitude of y.

If x or y is NaN, NaN is returned. If y is 0, NaN is returned and errno is set to EDOM. If x is +-Inf, NaN is returned. If y is non-zero, fmod(+-0,y) returns the value of x. If x is not +-Inf, fmod(x,+-Inf) returns the value of x.

The fmod() function may fail if:

EDOM

y is 0.

No other errors will occur.

Portable applications should not call fmod() with y equal to 0, because the result is implementation-dependent. The application should verify y is non-zero before calling fmod().

An application wishing to check for error situations should set errno to 0 before calling fmod(). If errno is non-zero on return, or the return value is NaN, an error has occurred.

See attributes(5) for descriptions of the following attributes:

isnan(3M), attributes(5)