fabs - absolute value function
#include <math.h> double fabs(double x);
The fabs() function computes the absolute value of x, |x|.
An application wishing to check for error situations should set errno to 0 before calling fabs(). If errno is non-zero on return, or the return value is NaN, an error has occurred.
Upon successful completion, fabs() returns the absolute value of x.
If x is NaN, NaN is returned and errno may be set to [EDOM].
If the result underflows, 0 is returned and errno may be set to [ERANGE].
The fabs() function may fail if:
- The value of x is NaN.
- The result underflows.
No other errors will occur.
Derived from Issue 1 of the SVID.