# log10(3M)

## NAME

log10 - base 10 logarithm function

## SYNOPSIS

cc [ *flag* ... ] *file* ... -lm [ *library* ... ]
#include <math.h>
double log10(double *x*);

## DESCRIPTION

The log10() function computes the base 10 logarithm of *x*,
log10(*x*). The value of *x* must be positive.

## RETURN VALUES

Upon successful completion, log10() returns the base 10 log-
arithm of *x*.
If *x* is NaN, NaN is returned. If *x* is less than 0, -HUGE_VAL
or NaN is returned, and *errno* is set to EDOM. If *x* is 0,
-HUGE_VAL is returned and errno may be set to ERANGE.
For exceptional cases, **matherr(3M)** tabulates the values to
be returned as dictated by Standards other than XPG4.

## ERRORS

The log10() function will fail if:
EDOM The value of *x* is negative.
The log10() function may fail if:
ERANGE
The value of *x* is 0.
No other errors will occur.

## USAGE

An application wishing to check for error situations should
set *errno* to 0 before calling log10(). If errno is non-zero
on return, or the return value is NaN, an error has
occurred.

## ATTRIBUTES

See **attributes(5)** for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________*|*_____________________________*|*
| MT-Level | MT-Safe |
|_____________________________*|*_____________________________*|*

## SEE ALSO

**isnan(3M)**, **log(3M)**, **matherr(3M)**, **pow(3M)**, **attributes(5)**,
**standards(5)**

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