56 lines
1.3 KiB
JavaScript
56 lines
1.3 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var sqrt = require( '@stdlib/math/base/special/sqrt' );
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// MAIN //
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/**
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* Returns a pseudorandom number drawn from a triangular distribution with minimum support `a`, maximum support `b` and mode `c`.
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*
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* @private
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* @param {PRNG} rand - PRNG for generating uniformly distributed numbers
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* @param {number} a - minimum support
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* @param {number} b - maximum support
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* @param {number} c - mode
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* @returns {number} pseudorandom number
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*/
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function triangular( rand, a, b, c ) {
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var fc;
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var x;
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var u;
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fc = (c - a) / (b - a);
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u = rand();
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if ( u < fc ) {
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x = (b - a) * (c - a);
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return a + sqrt( x * u );
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}
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x = (b - a) * (b - c);
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return b - sqrt( x * (1.0 - u) );
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}
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// EXPORTS //
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module.exports = triangular;
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