All files / stats/base/dists/discrete-uniform/pmf/lib factory.js

100% Statements 84/84
100% Branches 15/15
100% Functions 2/2
100% Lines 84/84

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 853x 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 3014x 3014x 3014x 3014x 3014x 3014x 3014x 3007x 3014x 10x 10x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3004x 3003x 1x 1x 3003x 2044x 2044x 958x 3003x 3014x 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 isInteger = require( '@stdlib/math/base/assert/is-integer' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
 
 
// MAIN //
 
/**
* Returns a function for evaluating the probability mass function (PMF) for a discrete uniform distribution with minimum support `a` and maximum support `b`.
*
* @param {integer} a - minimum support
* @param {integer} b - maximum support
* @returns {Function} PMF
*
* @example
* var pmf = factory( 0, 10 );
* var y = pmf( 2.0 );
* // returns ~0.091
*
* y = pmf( 12.0 );
* // returns 0.0
*/
function factory( a, b ) {
	var ninv;
	if (
		isnan( a ) ||
		isnan( b ) ||
		!isInteger( a ) ||
		!isInteger( b ) ||
		a > b
	) {
		return constantFunction( NaN );
	}
	ninv = 1.0 / ( b - a + 1.0 );
	return pmf;
 
	/**
	* Evaluates the probability mass function (PMF) for a discrete uniform distribution.
	*
	* @private
	* @param {number} x - input value
	* @returns {number} evaluated PMF
	*
	* @example
	* var y = pmf( 2.0 );
	* // returns <number>
	*/
	function pmf( x ) {
		if ( isnan( x ) ) {
			return NaN;
		}
		if ( x < a || x > b || !isInteger( x ) ) {
			return 0.0;
		}
		return ninv;
	}
}
 
 
// EXPORTS //
 
module.exports = factory;