Obtain the natural logarithm
[Classification]
Mathematical library
[Syntax]
#include <math.h>
double __far log(double x);
[Return value]
Returns the natural logarithm of x.
logf returns a Not-a-Number (NaN) and sets macro EDOM to global variable errno if x is negative.
If x is zero, it returns - and sets macro ERANGE to global variable errno.
[Description]
This function calculates the natural logarithm of x, i.e., logarithm with base e.