time-to-botec/js/node_modules/@stdlib/math/base/special/log2/README.md

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# Binary Logarithm
> Evaluate the [binary logarithm][binary-logarithm].
<section class="intro">
The [binary logarithm][binary-logarithm] (logarithm with base 2) is defined for any positive real number as
<!-- <equation class="equation" label="eq:binary_logarithm" align="center" raw="\quad \log_{2} \left( x \right) = y \quad \text{such that} \quad 2^y = x" alt="Equation for the binary logarithm."> -->
<div class="equation" align="center" data-raw-text="\quad \log_{2} \left( x \right) = y \quad \text{such that} \quad 2^y = x" data-equation="eq:binary_logarithm">
<img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@8cb4d022f6163be6523964802725ed2a74f2497b/lib/node_modules/@stdlib/math/base/special/log2/docs/img/equation_binary_logarithm.svg" alt="Equation for the binary logarithm.">
<br>
</div>
<!-- </equation> -->
</section>
<!-- /.intro -->
<section class="usage">
## Usage
```javascript
var log2 = require( '@stdlib/math/base/special/log2' );
```
#### log2( x )
Evaluates the [binary logarithm][binary-logarithm].
```javascript
var v = log2( 4.0 );
// returns 2.0
v = log2( 0.0 );
// returns -Infinity
v = log2( Infinity );
// returns Infinity
v = log2( NaN );
// returns NaN
```
For negative numbers, the [binary logarithm][binary-logarithm] is **not** defined.
```javascript
var v = log2( -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 log2 = require( '@stdlib/math/base/special/log2' );
var x;
var i;
for ( i = 0; i < 100; i++ ) {
x = round( randu() * 100.0 );
console.log( 'log2(%d) = %d', x, log2( x ) );
}
```
</section>
<!-- /.examples -->
<section class="links">
[binary-logarithm]: https://en.wikipedia.org/wiki/Binary_logarithm
</section>
<!-- /.links -->