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

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@license Apache-2.0
Copyright (c) 2018 The Stdlib Authors.
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# Havercosine
> Compute the half-value [versed cosine][versed-cosine].
<section class="intro">
The half-value [versed cosine][versed-cosine] is defined as
<!-- <equation class="equation" label="eq:havercosine" align="center" raw="\operatorname{havercos}(\theta) = \frac{1 + \cos \theta}{2}" alt="Haversed cosine."> -->
<div class="equation" align="center" data-raw-text="\operatorname{havercos}(\theta) = \frac{1 + \cos \theta}{2}" data-equation="eq:havercosine">
<img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@bb29798906e119fcb2af99e94b60407a270c9b32/lib/node_modules/@stdlib/math/base/special/havercos/docs/img/equation_havercosine.svg" alt="Haversed cosine.">
<br>
</div>
<!-- </equation> -->
</section>
<!-- /.intro -->
<section class="usage">
## Usage
```javascript
var havercos = require( '@stdlib/math/base/special/havercos' );
```
#### havercos( x )
Computes the half-value [versed cosine][versed-cosine] (in radians).
```javascript
var v = havercos( 0.0 );
// returns 1.0
v = havercos( 3.141592653589793/2.0 );
// returns 0.5
v = havercos( -3.141592653589793/6.0 );
// returns ~0.9330
```
</section>
<!-- /.usage -->
<section class="examples">
## Examples
<!-- eslint no-undef: "error" -->
```javascript
var linspace = require( '@stdlib/array/linspace' );
var TWO_PI = require( '@stdlib/constants/float64/two-pi' );
var havercos = require( '@stdlib/math/base/special/havercos' );
var x = linspace( 0.0, TWO_PI, 100 );
var i;
for ( i = 0; i < x.length; i++ ) {
console.log( havercos( x[ i ] ) );
}
```
</section>
<!-- /.examples -->
<section class="links">
[versed-cosine]: https://en.wikipedia.org/wiki/Versine
</section>
<!-- /.links -->