Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 | 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 27x 27x 27x 27x 27x 14x 27x 17x 17x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 114x 1x 1x 114x 7x 7x 106x 114x 3x 1x 1x 3x 1x 1x 1x 1x 114x 3x 1x 1x 3x 1x 1x 1x 1x 100x 114x 27x 3x 3x 3x 3x 3x | /**
* @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.
*/
'use strict';
// MODULES //
var constantFunction = require( '@stdlib/utils/constant-function' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var pow = require( '@stdlib/math/base/special/pow' );
var PINF = require( '@stdlib/constants/float64/pinf' );
// MAIN //
/**
* Returns a function for evaluating the probability density function (PDF) for a Kumaraswamy's double bounded distribution with first shape parameter `a` and second shape parameter `b`.
*
* @param {PositiveNumber} a - first shape parameter
* @param {PositiveNumber} b - second shape parameter
* @returns {Function} PDF
*
* @example
* var pdf = factory( 0.5, 0.5 );
*
* var y = pdf( 0.8 );
* // returns ~0.86
*
* y = pdf( 0.3 );
* // returns ~0.679
*/
function factory( a, b ) {
if (
isnan( a ) ||
isnan( b ) ||
a <= 0.0 ||
b <= 0.0
) {
return constantFunction( NaN );
}
return pdf;
/**
* Evaluates the probability density function (PDF) for a Kumaraswamy's double bounded distribution.
*
* @private
* @param {number} x - input value
* @returns {number} evaluated PDF
*
* @example
* var y = pdf( 2.0 );
* // returns <number>
*/
function pdf( x ) {
if ( isnan( x ) ) {
return NaN;
}
if ( x < 0.0 || x > 1.0 ) {
return 0.0;
}
// At the boundaries of the support, the density is infinite, finite, or zero depending on whether the corresponding shape parameter is less than, equal to, or greater than one:
if ( x === 0.0 ) {
if ( a < 1.0 ) {
return PINF;
}
if ( a > 1.0 ) {
return 0.0;
}
return b;
}
if ( x === 1.0 ) {
if ( b < 1.0 ) {
return PINF;
}
if ( b > 1.0 ) {
return 0.0;
}
return a;
}
return ( a*b ) * pow( x, a - 1.0 ) * pow( 1.0 - pow( x, a ), b - 1.0 );
}
}
// EXPORTS //
module.exports = factory;
|