Calculates the natural logarithm of a floating-point number.
[Format]
#include <mathf.h>
float logf (float f);
[Parameters]
f Floating-point number for which natural logarithm is to be computed
[Return values]
Normal: Natural logarithm of f
Abnormal: Domain error: Returns not-a-number.
[Remarks]
A domain error occurs if f is negative.
A range error occurs if f is 0.0.