Returns the next machine-representable number following x in the
    direction of y.

    This function is supported on OpenVMS Integrity servers and
    Alpha only.

    Format

      #include  <math.h>

      double nextafter  (double x, double y);

      float nextafterf  (float x, float y);

      long double nextafterl  (long double x, long double y);

1 - Arguments

 x

    A real number.

 y

    A real number.

2 - Description

    The nextafter functions return the next machine-representable
    floating-point number following x in the direction of y. If
    y is less than x, nextafter returns the largest representable
    floating-point number less than x.

3 - Return Values

    n                  The next representable floating-point value
                       following x in the direction of y.
    HUGE_VAL           Overflow; errno is set to ERANGE.
    NaN                x or y is NaN; errno is set to EDOM.