log1p(3M)

NAME

log1p − compute natural logarithm

cc [ flag ... ] file ... −lm [ library ... ]

#include <math.h>

double log1p(double x);

The log1p() function computes loge(1.0 + x). The value of x must be greater than −1.0.

Upon successful completion, log1p() returns the natural logarithm of 1.0 + x.

If x is NaN, log1p() returns NaN.

If x is less than −1.0, log1p() returns −HUGE_VAL or NaN and sets errno to EDOM.

If x is −1.0, log1p() returns −HUGE_VAL and may set errno to ERANGE.

For exceptional cases, matherr(3M) tabulates the values to be returned as dictated by Standards other than XPG4.

The log1p() function will fail if:

EDOM The value of x is less than −1.0.

The log1p() function may fail and set errno to:

ERANGE The value of x is −1.0.

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
MT-Level	MT-Safe