Synopsis
double log(double x);
Description

log computes the base-e logarithm of x.

If x = 0, errno is set to ERANGE and log returns −HUGE_VAL. If x < 0, errno is set to EDOM and log returns −HUGE_VAL.

If x < 0 or x = −∞, log returns NaN.
If x = 0, log returns −∞.
If x = ∞, log returns ∞.
If x = NaN, log returns x.