Returns the floating-point remainder r = x - n*y) when y is
    nonzero.
    This function is OpenVMS Alpha and Integrity servers only.
    Format
      #include  <math.h>
      double remainder  (double x, double y);
      float remainderf  (float x, float y);
      long double remainderl  (long double x, long double y);
1 – Argument
 x
    A real number.
 y
    A real number.
2 – Description
    These functions return the floating-point remainder r = x - n*y)
    when y is nonzero. The value n is the integral value nearest the
    exact value x/y. That is, n = rint(x/y).
    When |n - x/y| = 1/2, the value n is chosen to be even.
    The behavior of the remainder function is independent of the
    rounding mode.
    The remainder functions are functionally equivalent to the remquo
    functions.
3 – Return Values
    r                  Upon successful completion, these functions
                       return the floating-point remainder r = x - ny
                       when y is nonzero.
    Nan                If x or y is Nan.