roundb.js (2113B)
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 isnan = require( './../../../../base/assert/is-nan' ); 24 var isInfinite = require( './../../../../base/assert/is-infinite' ); 25 var pow = require( './../../../../base/special/pow' ); 26 var round = require( './../../../../base/special/round' ); 27 var roundn = require( './../../../../base/special/roundn' ); 28 29 30 // MAIN // 31 32 /** 33 * Rounds a numeric value to the nearest multiple of \\(b^n\\) on a linear scale. 34 * 35 * @param {number} x - input value 36 * @param {integer} n - integer power 37 * @param {PositiveInteger} b - base 38 * @returns {number} rounded value 39 * 40 * @example 41 * // Round a value to 2 decimal places: 42 * var v = roundb( 3.141592653589793, -2, 10 ); 43 * // returns 3.14 44 * 45 * @example 46 * // If n = 0 or b = 1, `roundb` behaves like `round`: 47 * var v = roundb( 3.141592653589793, 0, 2 ); 48 * // returns 3.0 49 * 50 * @example 51 * // Round a value to the nearest multiple of two: 52 * var v = roundb( 5.0, 1, 2 ); 53 * // returns 6.0 54 */ 55 function roundb( x, n, b ) { 56 var y; 57 var s; 58 if ( 59 isnan( x ) || 60 isnan( n ) || 61 isnan( b ) || 62 b <= 0 || 63 isInfinite( n ) || 64 isInfinite( b ) 65 ) { 66 return NaN; 67 } 68 if ( isInfinite( x ) || x === 0.0 ) { 69 return x; 70 } 71 if ( b === 10 ) { 72 return roundn( x, n ); 73 } 74 if ( n === 0 || b === 1 ) { 75 return round( x ); 76 } 77 s = pow( b, -n ); 78 79 // Check for overflow: 80 if ( isInfinite( s ) ) { 81 return x; 82 } 83 y = round( x * s ) / s; 84 85 // Check for overflow: 86 if ( isInfinite( y ) ) { 87 return x; 88 } 89 return y; 90 } 91 92 93 // EXPORTS // 94 95 module.exports = roundb;