# LOG10

## NAME

log10, log10f, log10l − base-10 logarithmic function

## SYNOPSIS

**#include <math.h>**

**double log10(double** *x***);**

float log10f(float *x***);**

long double log10l(long double *x***);**

Link with *−lm*.

Feature Test Macro Requirements for glibc (see **feature_test_macros(7)**):

**log10f**(), **log10l**():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

|| /* Since glibc 2.19: */ _DEFAULT_SOURCE

|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

## DESCRIPTION

These functions return the base 10 logarithm of *x*.

## RETURN VALUE

On success, these functions return the base 10 logarithm of *x*.

For special cases, including where *x* is 0, 1, negative, infinity, or NaN, see **log(3)**.

## ERRORS

See **math_error(7)** for information on how to determine whether an error has occurred when calling these functions.

For a discussion of the errors that can occur for these functions, see **log(3)**.

## ATTRIBUTES

For an explanation of the terms used in this section, see **attributes(7)**.

## CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

The variant returning *double* also conforms to SVr4, 4.3BSD, C89.

## SEE ALSO

**cbrt(3)**, **clog10(3)**, **exp10(3)**, **log(3)**, **log2(3)**, **sqrt(3)**

## COLOPHON

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