time-to-botec

Benchmark sampling in different programming languages
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main.js (2378B)

      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 reldiff = require( './../../../../base/utils/relative-difference' );
     24 var isnan = require( './../../../../base/assert/is-nan' );
     25 var PINF = require( '@stdlib/constants/float64/pinf' );
     26 var MAX_FLOAT64 = require( '@stdlib/constants/float64/max' );
     27 var EPS = require( '@stdlib/constants/float64/eps' );
     28 
     29 
     30 // VARIABLES //
     31 
     32 var MAX_DIFF = MAX_FLOAT64 * EPS;
     33 
     34 
     35 // MAIN //
     36 
     37 /**
     38 * Computes the relative difference in units of double-precision floating-point epsilon.
     39 *
     40 * @param {number} x - first number
     41 * @param {number} y - second number
     42 * @param {(string|Function)} [scale='max-abs'] - scale function
     43 * @returns {number} relative difference in units of double-precision floating-point epsilon
     44 *
     45 * @example
     46 * var d = epsilonDifference( 12.15, 12.149999999999999 ); // => ~0.658ε
     47 * // returns ~0.658
     48 *
     49 * @example
     50 * var d = epsilonDifference( 2.4341309458983933, 2.4341309458633909, 'mean-abs' ); // => ~64761.5ε => ~1.438e-11
     51 * // returns ~64761.5
     52 *
     53 * @example
     54 * function scale( x, y ) {
     55 *      // Return the minimum value:
     56 *      return ( x > y ) ? y : x;
     57 * }
     58 *
     59 * var d = epsilonDifference( 1.0000000000000002, 1.0000000000000100, scale ); // => ~44ε
     60 * // returns ~44
     61 */
     62 function epsilonDifference( x, y, scale ) {
     63 	var d = reldiff( x, y, scale || 'max-abs' );
     64 
     65 	// If `d` is `NaN` or `+infinity`, nothing we can do...
     66 	if ( isnan( d ) || d === PINF ) {
     67 		return d;
     68 	}
     69 	// If `d >= MAX_VALUE`, we will overflow, as `EPS <<< 1`. To prevent overflow, we cap out at the maximum double-precision floating-point number...
     70 	if ( d >= MAX_DIFF ) {
     71 		return MAX_FLOAT64;
     72 	}
     73 	// Return the answer to the question: how many EPS increments is the relative difference?
     74 	return d / EPS;
     75 }
     76 
     77 
     78 // EXPORTS //
     79 
     80 module.exports = epsilonDifference;