main.js (1376B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var evalpoly = require( './../../../../base/tools/evalpoly' ); 24 var pow = require( './../../../../base/special/pow' ); 25 var abs = require( './../../../../base/special/abs' ); 26 var coefficients = require( './coefficients.js' ); 27 28 29 // MAIN // 30 31 /** 32 * Evaluates a Lucas polynomial. 33 * 34 * @param {integer} n - Lucas polynomial to evaluate 35 * @param {number} x - value at which to evaluate a Lucas polynomial 36 * @returns {number} result 37 * 38 * @example 39 * var v = lucaspoly( 5, 1.0 ); 40 * // returns 11.0 41 */ 42 function lucaspoly( n, x ) { 43 var coefs; 44 var an; 45 var v; 46 47 an = abs( n ); 48 coefs = coefficients( an ); 49 50 v = evalpoly( coefs, x ); 51 if ( n >= 0 ) { 52 return v; 53 } 54 return pow( -1.0, an ) * v; 55 } 56 57 58 // EXPORTS // 59 60 module.exports = lucaspoly;