Returns the length of the hypotenuse of a right triangle.
    Format
      #include  <math.h>
      double hypot  (double x, double y);
      float hypotf  (float x, float y); (Integrity servers, Alpha)
      long double hypotl  (long double x, long double y);
                          (Integrity servers, Alpha)
1 – Arguments
 x
    A real value.
 y
    A real value.
2 – Description
    The hypot functions return the length of the hypotenuse of a
    right triangle, where x and y represent the perpendicular sides
    of the triangle. The length is calculated as:
    sqrt(x2 + y2)
    On overflow, the return value is undefined, and errno is set to
    ERANGE.
3 – Return Values
    x                  The length of the hypotenuse.
    HUGE_VAL           Overflow occurred; errno is set to ERANGE.
    0                  Underflow occurred; errno is set to ERANGE.
    NaN                x or y is NaN; errno is set to EDOM.