eps1.js (1179B)
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 abs = require( './../../../../base/special/abs' ); 24 var ln = require( './../../../../base/special/ln' ); 25 var lambdaeta = require( './lambdaeta.js' ); 26 var rateval = require( './rational_ak0bk0.js' ); 27 28 29 // MAIN // 30 31 /** 32 * Evaluates the `eps1` function. 33 * 34 * @private 35 * @param {number} eta - eta value 36 * @returns {number} function value 37 */ 38 function eps1( eta ) { 39 var la; 40 if ( abs( eta ) < 1.0 ) { 41 return rateval( eta ); 42 } 43 la = lambdaeta( eta ); 44 return ln( eta / ( la - 1.0 ) ) / eta; 45 } 46 47 48 // EXPORTS // 49 50 module.exports = eps1;