# Man

Command Section
```LOG(3)                 FreeBSD Library Functions Manual                 LOG(3)

NAME
log, logf, logl, log10, log10f, log10l, log2, log2f, log2l, log1p,
log1pf, log1pl - logarithm functions

LIBRARY
Math Library (libm, -lm)

SYNOPSIS
#include <math.h>

double
log(double x);

float
logf(float x);

long double
logl(long double x);

double
log10(double x);

float
log10f(float x);

long double
log10l(long double x);

double
log2(double x);

float
log2f(float x);

long double
log2l(long double x);

double
log1p(double x);

float
log1pf(float x);

long double
log1pl(long double x);

DESCRIPTION
The log(), logf(), and logl() functions compute the natural logarithm of
x.

The log10(), log10f(), and log10l() functions compute the logarithm base
10 of x, while log2(), log2f(), and log2l() compute the logarithm base 2
of x.

The log1p(), log1pf(), and log1pl() functions compute the natural
logarithm of 1 + x.  Computing the natural logarithm as log1p(x) is more
accurate than computing it as log(1 + x) when x is close to zero.

RETURN VALUES
These functions return the requested logarithm; the logarithm of 1 is +0.
An attempt to take the logarithm of +-0 results in a divide-by-zero
exception, and -infinity is returned.  Otherwise, attempting to take the
logarithm of a negative number results in an invalid exception and a
return value of NaN.