double remainder(double x, double y);
float remainderf(float x, float y);
long double remainderl(long double x, long double y);
These functions shall return the floating-point remainder r= x- ny when y is non-zero. The value n is the integral value nearest the exact value x/ y. When |n-x/y|=0.5, the value n is chosen to be even.
The behavior of remainder() shall be independent of the rounding mode.
Upon successful completion, these functions shall return the floating-point remainder r= x- ny when y is non-zero.
If x or y is NaN, a NaN shall be returned.
If x is infinite or y is 0 and the other is non-NaN, a domain error shall occur, and either a NaN (if supported), or an implementation-defined value shall be returned.
These functions shall fail if:
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.
The following sections are informative.
On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero.
abs() , div() , feclearexcept() , fetestexcept() , ldiv() , the Base Definitions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Conditions for Mathematical Functions, <math.h>