README.md (4217B)
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 # Mean 22 23 > [Kumaraswamy's double bounded][kumaraswamy-distribution] distribution [expected value][mean]. 24 25 <!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. --> 26 27 <section class="intro"> 28 29 The [mean][mean] for a [Kumaraswamy's double bounded][kumaraswamy-distribution] random variable is 30 31 <!-- <equation class="equation" label="eq:kumaraswamy_mean" align="center" raw="\mathbb{E} \left[ X \right] = {b\Gamma(1+{\tfrac {1}{a}})\Gamma(b)}{\Gamma(1+{\tfrac{1}{a}}+b)}" alt="Mean for a Kumaraswamy's double bounded distribution."> --> 32 33 <div class="equation" align="center" data-raw-text="\mathbb{E} \left[ X \right] = {b\Gamma(1+{\tfrac {1}{a}})\Gamma(b)}{\Gamma(1+{\tfrac{1}{a}}+b)}" data-equation="eq:kumaraswamy_mean"> 34 <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@51534079fef45e990850102147e8945fb023d1d0/lib/node_modules/@stdlib/stats/base/dists/kumaraswamy/mean/docs/img/equation_kumaraswamy_mean.svg" alt="Mean for a Kumaraswamy's double bounded distribution."> 35 <br> 36 </div> 37 38 <!-- </equation> --> 39 40 where `a` is the first shape parameter, `b` the second shape parameter, and `Γ` denotes the [gamma function][gamma-function]. 41 42 </section> 43 44 <!-- /.intro --> 45 46 <!-- Package usage documentation. --> 47 48 <section class="usage"> 49 50 ## Usage 51 52 ```javascript 53 var mean = require( '@stdlib/stats/base/dists/kumaraswamy/mean' ); 54 ``` 55 56 #### mean( a, b ) 57 58 Returns the [expected value][mean] of a [Kumaraswamy's double bounded][kumaraswamy-distribution] distribution with first shape parameter `a` and second shape parameter `b`. 59 60 ```javascript 61 var v = mean( 1.5, 1.5 ); 62 // returns ~0.512 63 64 v = mean( 4.0, 12.0 ); 65 // returns ~0.481 66 67 v = mean( 2.0, 8.0 ); 68 // returns ~0.3 69 ``` 70 71 If provided `NaN` as any argument, the function returns `NaN`. 72 73 ```javascript 74 var v = mean( NaN, 2.0 ); 75 // returns NaN 76 77 v = mean( 2.0, NaN ); 78 // returns NaN 79 ``` 80 81 If provided `a <= 0`, the function returns `NaN`. 82 83 ```javascript 84 var y = mean( -1.0, 2.0 ); 85 // returns NaN 86 87 y = mean( 0.0, 2.0 ); 88 // returns NaN 89 ``` 90 91 If provided `b <= 0`, the function returns `NaN`. 92 93 ```javascript 94 var y = mean( 2.0, -1.0 ); 95 // returns NaN 96 97 y = mean( 2.0, 0.0 ); 98 // returns NaN 99 ``` 100 101 </section> 102 103 <!-- /.usage --> 104 105 <!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> 106 107 <section class="notes"> 108 109 </section> 110 111 <!-- /.notes --> 112 113 <!-- Package usage examples. --> 114 115 <section class="examples"> 116 117 ## Examples 118 119 <!-- eslint no-undef: "error" --> 120 121 ```javascript 122 var randu = require( '@stdlib/random/base/randu' ); 123 var mean = require( '@stdlib/stats/base/dists/kumaraswamy/mean' ); 124 125 var a; 126 var b; 127 var v; 128 var i; 129 130 for ( i = 0; i < 10; i++ ) { 131 a = randu() * 10.0; 132 b = randu() * 10.0; 133 v = mean( a, b ); 134 console.log( 'a: %d, b: %d, E(X;a,b): %d', a.toFixed( 4 ), b.toFixed( 4 ), v.toFixed( 4 ) ); 135 } 136 ``` 137 138 </section> 139 140 <!-- /.examples --> 141 142 <!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> 143 144 <section class="references"> 145 146 </section> 147 148 <!-- /.references --> 149 150 <!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> 151 152 <section class="links"> 153 154 [gamma-function]: https://en.wikipedia.org/wiki/Gamma_function 155 156 [kumaraswamy-distribution]: https://en.wikipedia.org/wiki/Kumaraswamy_distribution 157 158 [mean]: https://en.wikipedia.org/wiki/Mean 159 160 </section> 161 162 <!-- /.links -->