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# Common Logarithm

> Evaluate the [common logarithm][common-logarithm].

<section class="intro">

The [common logarithm][common-logarithm] (logarithm with base 10) is defined for any positive real number as

<!-- <equation class="equation" label="eq:common_logarithm" align="center" raw="\quad \log_{10} \left( x \right) = y \quad \text{such\ that} \quad 10^y = x" alt="Equation for the common logarithm."> -->

<div class="equation" align="center" data-raw-text="\quad \log_{10} \left( x \right) = y \quad \text{such\ that} \quad 10^y = x" data-equation="eq:common_logarithm">
    <img src="https://cdn.rawgit.com/stdlib-js/stdlib/7e0a95722efd9c771b129597380c63dc6715508b/lib/node_modules/@stdlib/math/base/special/log10/docs/img/equation_common_logarithm.svg" alt="Equation for the common logarithm.">
    <br>
</div>

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="usage">

## Usage

```javascript
var log10 = require( '@stdlib/math/base/special/log10' );
```

#### log10( x )

Evaluates the [common logarithm][common-logarithm].

```javascript
var v = log10( 100.0 );
// returns 2.0

v = log10( 8.0 );
// returns ~0.903

v = log10( 0.0 );
// returns -Infinity

v = log10( Infinity );
// returns Infinity

v = log10( NaN );
// returns NaN
```

For negative numbers, the [common logarithm][common-logarithm] is **not** defined.

```javascript
var v = log10( -4.0 );
// returns NaN
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var log10 = require( '@stdlib/math/base/special/log10' );

var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = round( randu() * 100.0 );
    console.log( 'log10(%d) = %d', x, log10( x ) );
}
```

</section>

<!-- /.examples -->

<section class="links">

[common-logarithm]: https://en.wikipedia.org/wiki/Common_logarithm

</section>

<!-- /.links -->
