Computes the floating-point remainder.
    Format
      #include  <math.h>
      double fmod  (double x, double y);
      float fmodf  (float x, float y); (Integrity servers, Alpha)
      long double fmodl  (long double x, long double y);
                         (Integrity servers, Alpha)
1 – Arguments
 x
    A real value.
 y
    A real value.
2 – Description
    The fmod functions return the floating-point remainder of the
    first argument divided by the second. If the second argument is
    0, the function returns 0.
3 – Return Values
    x                  The value f, which has the same sign as the
                       argument x, such that x == i * y + f for some
                       integer i, where the magnitude of f is less
                       than the magnitude of y.
    0                  Indicates that y is 0.