fdim(3M)

fdim -- return positive difference between two arguments

Synopsis

   cc [flag ...] file ...  -lm [library ...]
   
   #include <math.h>
   

   double fdim(double x, double y);
   

   float fdimf(float x, float y);
   

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

Description

fdim, fdimf and fdiml return the positive difference between the x and y arguments. If x is greater than y then the difference between the two is returned. If x is less than or equal to y then +0 is returned.

Errors

If x is + and y is - (or vice versa) fdim, fdimf and fdiml return IEEE NaN on systems that support it and raise the invalid operation exception. Otherwise, they return 0. errno is set to ERANGE.

If x - y overflows fdim, fdimf and fdiml return ±HUGE_VAL, ±HUGE_VALF or ±HUGE_VALL (respectively) and errno is set to ERANGE.

On systems that support IEEE NaN, if the argument to any of these functions is a quiet NaN, that value is returned. If the argument is a signaling NaN, a quiet NaN is returned and the invalid operation exception is raised. In either case, errno is set to EDOM.

If the program was compiled with the -Xt compilation mode, a value that will compare equal to HUGE is returned instead of HUGE_VAL. These error handling procedures may be changed with the function matherr.

References

cc(1), matherr(3M),