All files factory.js

100% Statements 82/82
100% Branches 12/12
100% Functions 2/2
100% Lines 82/82

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 833x 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 3013x 3013x 3013x 3013x 3008x 3013x 9x 9x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3003x 1x 1x 3003x 2314x 2314x 688x 3003x 3013x 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 ln = require( '@stdlib/math/base/special/ln' );
var LN_PI = require( '@stdlib/constants/float64/ln-pi' );
var NINF = require( '@stdlib/constants/float64/ninf' );
 
 
// MAIN //
 
/**
* Returns a function for evaluating the logarithm of the probability density function (PDF) for an arcsine distribution with minimum support `a` and maximum support `b`.
*
* @param {number} a - minimum support
* @param {number} b - maximum support
* @returns {Function} logPDF
*
* @example
* var logpdf = factory( 0.0, 10.0 );
* var y = logpdf( 2.0 );
* // returns ~-2.531
*
* y = logpdf( 12.0 );
* // returns -Infinity
*/
function factory( a, b ) {
	if (
		isnan( a ) ||
		isnan( b ) ||
		a >= b
	) {
		return constantFunction( NaN );
	}
	return logpdf;
 
	/**
	* Evaluates the logarithm of the probability density function (PDF) for an arcsine distribution.
	*
	* @private
	* @param {number} x - input value
	* @returns {number} evaluated logPDF
	*
	* @example
	* var y = logpdf( 2.0 );
	* // returns <number>
	*/
	function logpdf( x ) {
		if ( isnan( x ) ) {
			return NaN;
		}
		if ( x < a || x > b ) {
			return NINF;
		}
		return -( LN_PI + ( ln( ( x-a ) * ( b-x ) ) / 2.0 ) );
	}
}
 
 
// EXPORTS //
 
module.exports = factory;