log - natural logarithm function
#include <math.h> double log(double x);
The log() function computes the natural logarithm of x, loge(x). The value of x must be positive.
An application wishing to check for error situations should set errno to 0 before calling log(). If errno is non-zero on return, or the return value is NaN, an error has occurred.
Upon successful completion, log() returns the natural logarithm of x.
If x is NaN, NaN is returned and errno may be set to [EDOM].
If x is less than 0, -HUGE_VAL or NaN is returned, and errno is set to [EDOM].
If x is 0, -HUGE_VAL is returned and errno may be set to [ERANGE].
The log() function will fail if:
- The value of x is negative.
The log() function may fail if:
- The value of x is NaN.
- The value of x is 0.
No other errors will occur.
exp(), isnan(), log10(), log1p(), <math.h>.
Derived from Issue 1 of the SVID.