README.md (1725B)
1 <!-- 2 3 @license Apache-2.0 4 5 Copyright (c) 2018 The Stdlib Authors. 6 7 Licensed under the Apache License, Version 2.0 (the "License"); 8 you may not use this file except in compliance with the License. 9 You may obtain a copy of the License at 10 11 http://www.apache.org/licenses/LICENSE-2.0 12 13 Unless required by applicable law or agreed to in writing, software 14 distributed under the License is distributed on an "AS IS" BASIS, 15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 See the License for the specific language governing permissions and 17 limitations under the License. 18 19 --> 20 21 # cospi 22 23 > Compute the [cosine][@stdlib/math/base/special/cos] of a number times [π][@stdlib/constants/float64/pi]. 24 25 <section class="usage"> 26 27 ## Usage 28 29 ```javascript 30 var cospi = require( '@stdlib/math/base/special/cospi' ); 31 ``` 32 33 #### cospi( x ) 34 35 Computes `cos(πx)` more accurately than `cos(pi*x)`, especially for large `x`. 36 37 ```javascript 38 var y = cospi( 0.0 ); 39 // returns 1.0 40 41 y = cospi( 0.5 ); 42 // returns 0.0 43 44 y = cospi( 0.1 ); 45 // returns ~0.951 46 47 y = cospi( NaN ); 48 // returns NaN 49 ``` 50 51 </section> 52 53 <!-- /.usage --> 54 55 <section class="examples"> 56 57 ## Examples 58 59 <!-- eslint no-undef: "error" --> 60 61 ```javascript 62 var linspace = require( '@stdlib/array/linspace' ); 63 var cospi = require( '@stdlib/math/base/special/cospi' ); 64 65 var x = linspace( -100.0, 100.0, 100 ); 66 var i; 67 68 for ( i = 0; i < x.length; i++ ) { 69 console.log( cospi( x[ i ] ) ); 70 } 71 ``` 72 73 </section> 74 75 <!-- /.examples --> 76 77 <section class="links"> 78 79 [@stdlib/math/base/special/cos]: https://www.npmjs.com/package/@stdlib/math/tree/main/base/special/cos 80 81 [@stdlib/constants/float64/pi]: https://www.npmjs.com/package/@stdlib/constants-float64-pi 82 83 </section> 84 85 <!-- /.links -->