com.google.javascript.jscomp.js.es6.math.expm1.js Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of closure-compiler-linter Show documentation

Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs. This binary checks for style issues such as incorrect or missing JSDoc usage, and missing goog.require() statements. It does not do more advanced checks such as typechecking.

There is a newer version: v20200830

Show newest version

/*
 * Copyright 2016 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @fileoverview Implements Math.expm1 polyfill
 * @suppress {uselessCode}
 */
'require util/polyfill';

$jscomp.polyfill('Math.expm1', function(orig) {
  if (orig) return orig;

  /**
   * Exponentiates x and then subtracts one.  This is implemented in a
   * way that is accurate for numbers close to zero.
   *
   * Polyfills the static function Math.expm1().
   *
   * @param {number} x Any number, or value that can be coerced to a number.
   * @return {number} The exponential of x, less 1.
   */
  var polyfill = function(x) {
    // This implementation is based on the Taylor expansion
    //   exp(x) ~ 1 + x + x^2/2 + x^3/6 + x^4/24 + ...
    x = Number(x);
    if (x < .25 && x > -.25) {
      var y = x;
      var d = 1;
      var z = x;
      var zPrev = 0;
      while (zPrev != z) {
        y *= x / (++d);
        z = (zPrev = z) + y;
      }
      return z;
    }
    return Math.exp(x) - 1;
  };

  return polyfill;
}, 'es6', 'es3');