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@stdlib/stats

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Standard library statistical functions.

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/** * @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'; // MAIN // /** * Returns the mode of a beta prime distribution. * * @param {PositiveNumber} alpha - first shape parameter * @param {PositiveNumber} beta - second shape parameter * @returns {PositiveNumber} mode * * @example * var v = mode( 1.0, 2.0 ); * // returns 0.0 * * @example * var v = mode( 4.0, 12.0 ); * // returns ~0.231 * * @example * var v = mode( 8.0, 2.0 ); * // returns ~2.333 * * @example * var v = mode( 1.0, 1.0 ); * // returns 0.0 * * @example * var v = mode( 1.0, -0.1 ); * // returns NaN * * @example * var v = mode( -0.1, 1.0 ); * // returns NaN * * @example * var v = mode( 2.0, NaN ); * // returns NaN * * @example * var v = mode( NaN, 2.0 ); * // returns NaN */ function mode( alpha, beta ) { if ( alpha <= 0.0 || beta <= 0.0 ) { return NaN; } if ( alpha < 1.0 ) { return 0.0; } return ( alpha - 1.0 ) / ( beta + 1.0 ); } // EXPORTS // module.exports = mode;