log1p, log1pf, log1pl - compute natural logarithm

Syntax	#include <math.h> double log1p(double x); C11 float log1pf(float x); long double log1pl(long double x); (End)
Description	These functions compute loge (1.0 + x), where x must be greater than -1.0.
Return val.	ln(1.0 + x)	if successful.
	-HUGE_VAL -HUGE_VALF -HUGE_VALL	depending on the function type, if x is less than or equal to -1. errno is set to indicate the error.
Errors	log1p(), log1pf() and log1pl() will fail if:
	EDOM	The value of x is less than -1.0.
See also	log(), math.h.