87 lines
1.8 KiB
Markdown
87 lines
1.8 KiB
Markdown
|
<!--
|
||
|
|
|
||
|
|
@license Apache-2.0
|
||
|
|
|
||
|
|
Copyright (c) 2018 The Stdlib Authors.
|
||
|
|
|
||
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
you may not use this file except in compliance with the License.
|
||
|
|
You may obtain a copy of the License at
|
||
|
|
|
||
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
|
||
|
|
Unless required by applicable law or agreed to in writing, software
|
||
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
See the License for the specific language governing permissions and
|
||
|
|
limitations under the License.
|
||
|
|
|
||
|
|
-->
|
||
|
|
|
||
|
|
# cosm1
|
||
|
|
|
||
|
|
> Compute `cos(x) - 1`.
|
||
|
|
|
||
|
|
<section class="usage">
|
||
|
|
|
||
|
|
## Usage
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
var cosm1 = require( '@stdlib/math/base/special/cosm1' );
|
||
|
|
```
|
||
|
|
|
||
|
|
#### cosm1( x )
|
||
|
|
|
||
|
|
Computes `cos(x) - 1`, where `cos` is the [cosine][@stdlib/math/base/special/cos] of a `number` (in radians). This function should be used instead of manually calculating `cos(x) - 1` when the argument is near unity.
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
var PI = require( '@stdlib/constants/float64/pi' );
|
||
|
|
|
||
|
|
var v = cosm1( 0.0 );
|
||
|
|
// returns 0.0
|
||
|
|
|
||
|
|
v = cosm1( PI/4.0 );
|
||
|
|
// returns ~-0.293
|
||
|
|
|
||
|
|
v = cosm1( -PI/6.0 );
|
||
|
|
// returns ~-0.134
|
||
|
|
|
||
|
|
v = cosm1( NaN );
|
||
|
|
// returns NaN
|
||
|
|
```
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.usage -->
|
||
|
|
|
||
|
|
<section class="examples">
|
||
|
|
|
||
|
|
## Examples
|
||
|
|
|
||
|
|
<!-- eslint no-undef: "error" -->
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
var linspace = require( '@stdlib/array/linspace' );
|
||
|
|
var PI = require( '@stdlib/constants/float64/pi' );
|
||
|
|
var cosm1 = require( '@stdlib/math/base/special/cosm1' );
|
||
|
|
|
||
|
|
var x = linspace( 0.0, 2.0*PI, 100 );
|
||
|
|
var i;
|
||
|
|
|
||
|
|
for ( i = 0; i < x.length; i++ ) {
|
||
|
|
console.log( cosm1( x[ i ] ) );
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.examples -->
|
||
|
|
|
||
|
|
<section class="links">
|
||
|
|
|
||
|
|
[@stdlib/math/base/special/cos]: https://www.npmjs.com/package/@stdlib/math/tree/main/base/special/cos
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
<!-- /.links -->
|