#include <math.h>
double remquo(double x, double y, int *quo);
float remquof(float x, float y, int *quo);
long double remquol(long double x, long double y,
int *quo);
The remquo(), remquof(), and remquol() functions shall compute the same remainder as the remainder(), remainderf(), and remainderl() functions, respectively. In the object pointed to by quo, they store a value whose sign is the sign of x/ y and whose magnitude is congruent modulo 2**n to the magnitude of the integral quotient of x/ y, where n is an implementation-defined integer greater than or equal to 3.
An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.
These functions shall return x REM y.
If x or y is NaN, a NaN shall be returned.
If x is ±Inf or y is zero and the other argument 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.
These functions are intended for implementing argument reductions which can exploit a few low-order bits of the quotient. Note that x may be so large in magnitude relative to y that an exact representation of the quotient is not practical.
feclearexcept(), fetestexcept(), remainder(), the Base Definitions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Conditions for Mathematical Functions, <math.h>