com.google.javascript.jscomp.js.es6.math.log1p.js Maven / Gradle / Ivy
/*
* 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.
*/
'require util/polyfill';
$jscomp.polyfill('Math.log1p', function(orig) {
if (orig) return orig;
/**
* Returns the natural logarithm of 1+x, implemented in a way that is
* accurate for numbers close to zero.
*
* Polyfills the static function Math.log1p().
*
* @param {number} x Any number, or value that can be coerced to a number.
* @return {number} The natural log of 1+x.
*/
var polyfill = function(x) {
// This implementation is based on the Taylor expansion
// log(1 + x) ~ x - x^2/2 + x^3/3 - x^4/4 + x^5/5 - ...
x = Number(x);
if (x < 0.25 && x > -0.25) {
var y = x;
var d = 1;
var z = x;
var zPrev = 0;
var s = 1;
while (zPrev != z) {
y *= x;
s *= -1;
z = (zPrev = z) + s * y / (++d);
}
return z;
}
return Math.log(1 + x);
};
return polyfill;
}, 'es6', 'es3');