91 lines
1.6 KiB
Markdown
91 lines
1.6 KiB
Markdown
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@license Apache-2.0
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Copyright (c) 2018 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# acos
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> Compute the [arccosine][arccosine] of a number.
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<section class="usage">
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## Usage
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```javascript
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var acos = require( '@stdlib/math/base/special/acos' );
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```
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#### acos( x )
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Computes the [arccosine][arccosine] of a `number` (in radians).
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```javascript
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var v = acos( 1.0 );
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// returns 0.0
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v = acos( 0.707 ); // ~pi/4
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// returns ~0.7855
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v = acos( 0.866 ); // ~pi/6
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// returns ~0.5236
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v = acos( NaN );
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// returns NaN
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```
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The domain of `x` is restricted to `[-1,1]`. If `|x| > 1`, the function returns `NaN`.
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```javascript
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var v = acos( -3.14 );
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// returns NaN
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```
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</section>
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<!-- /.usage -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var linspace = require( '@stdlib/array/linspace' );
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var acos = require( '@stdlib/math/base/special/acos' );
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var x = linspace( -1.0, 1.0, 100 );
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var i;
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for ( i = 0; i < x.length; i++ ) {
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console.log( acos( x[ i ] ) );
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}
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```
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</section>
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<!-- /.examples -->
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<section class="links">
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[arccosine]: https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
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</section>
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<!-- /.links -->
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