# log10 man page

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).

Interface | Attribute | Value |
---|---|---|

log10(), log10f(), log10l() | Thread safety | MT-Safe |

## Conforming to

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

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

## See Also

## Colophon

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## Referenced By

log10f(3) and log10l(3) are aliases of log10(3).