Calculates the remainder of a division of two floating-point numbers.
double fmod (double x, double y);
float fmodf (float x, float y);
long double fmodl (long double x, long double y);
When y is not 0.0: Remainder of division of x by y
When x is ±∞ or y is 0: Returns not-a-number and sets global variable errno to the value of macro EDOM.
In the fmod function, the relationship between parameters x and y and return value ret is as follows:
x = y * i + ret (where i is an integer)
The sign of return value ret is the same as the sign of x.
If the quotient of x/y cannot be represented, the value of the result is not guaranteed.