### 1.19 `fdim`, `fdimf`–positive difference

Synopsis

         #include <math.h>
         double fdim(double x, double y);
         float fdimf(float x, float y);

Description
The `fdim` functions determine the positive difference between their arguments, returning:

         	x - y	if x > y, or

         	+0	if x <= y, or

         	NAN	if either argument is NAN.

A range error may occur.

Returns
The `fdim` functions return the positive difference value.

Portability
ANSI C, POSIX.