todouble.js (1132B)
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 pow = require( '@stdlib/math/base/special/pow' ); 24 25 26 // MAIN // 27 28 /** 29 * Converts a double's fraction bit sequence to a numeric value. 30 * 31 * @private 32 * @param {string} frac - literal bit representation of a double's fraction bit sequence 33 * @returns {number} fraction) 34 */ 35 function toDouble( frac ) { 36 var sum = 0; 37 var i; 38 for ( i = 0; i < frac.length; i++ ) { 39 if ( frac[ i ] === '1' ) { 40 sum += pow( 2.0, -(i+1) ); 41 } 42 } 43 return sum; 44 } 45 46 47 // EXPORTS // 48 49 module.exports = toDouble;