fdim, fdimf, fdiml - positive difference

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

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

These functions return the positive difference, max(x-y,0), between their arguments.

On success, these functions return the positive difference.

If x or y is a NaN, a NaN is returned.

If the result overflows, a range error occurs, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively.

fmax(3)