README.md (2773B)
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 # y1 22 23 > Compute the [Bessel function of the second kind][bessel-second-kind] of order one. 24 25 <section class="intro"> 26 27 The [Bessel function of the second kind][bessel-second-kind] of order one is defined as 28 29 <!-- <equation class="equation" label="eq:bessel_second_kind_order_one" align="center" raw="Y_1(x) = \frac{1}{\pi} \int_0^\pi \sin(x \sin\theta - \theta) \, d\theta -\frac{1}{\pi} \int_0^\infty \left[ e^t - e^{-t} \right] e^{-x \sinh t} \, dt" alt="Bessel function of the second kind of order one"> --> 30 31 <div class="equation" align="center" data-raw-text="Y_1(x) = \frac{1}{\pi} \int_0^\pi \sin(x \sin\theta - \theta) \, d\theta -\frac{1}{\pi} \int_0^\infty \left[ e^t - e^{-t} \right] e^{-x \sinh t} \, dt" data-equation="eq:bessel_second_kind_order_one"> 32 <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@591cf9d5c3a0cd3c1ceec961e5c49d73a68374cb/lib/node_modules/@stdlib/math/base/special/bessely1/docs/img/equation_bessel_second_kind_order_one.svg" alt="Bessel function of the second kind of order one"> 33 <br> 34 </div> 35 36 <!-- </equation> --> 37 38 </section> 39 40 <!-- ./intro --> 41 42 <section class="usage"> 43 44 ## Usage 45 46 ```javascript 47 var y1 = require( '@stdlib/math/base/special/bessely1' ); 48 ``` 49 50 #### y1( x ) 51 52 Computes the [Bessel function of the second kind][bessel-second-kind] of order one at `x`. 53 54 ```javascript 55 var v = y1( 0.0 ); 56 // returns -Infinity 57 58 v = y1( 1.0 ); 59 // returns ~-0.781 60 61 v = y1( Infinity ); 62 // returns 0.0 63 ``` 64 65 If `x < 0` or `x` is `NaN`, the function returns `NaN`. 66 67 ```javascript 68 var v = y1( -1.0 ); 69 // returns NaN 70 71 v = y1( -Infinity ); 72 // returns NaN 73 74 v = y1( NaN ); 75 // returns NaN 76 77 ``` 78 79 </section> 80 81 <!-- /.usage --> 82 83 <section class="examples"> 84 85 ## Examples 86 87 <!-- eslint no-undef: "error" --> 88 89 ```javascript 90 var randu = require( '@stdlib/random/base/randu' ); 91 var y1 = require( '@stdlib/math/base/special/bessely1' ); 92 93 var x; 94 var i; 95 96 for ( i = 0; i < 100; i++ ) { 97 x = randu() * 10.0; 98 console.log( 'y1(%d) = %d', x, y1( x ) ); 99 } 100 ``` 101 102 </section> 103 104 <!-- /.examples --> 105 106 <section class="links"> 107 108 [bessel-second-kind]: https://en.wikipedia.org/wiki/Bessel_function#Bessel_functions_of_the_second_kind:_Y.CE.B1 109 110 </section> 111 112 <!-- /.links -->