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

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/*
 * 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.tanh', function(orig) {
  if (orig) return orig;

  /**
   * Computes the hyperbolic tangent.
   *
   * Polyfills the static function Math.tanh().
   *
   * @param {number} x Any number, or value that can be coerced to a number.
   * @return {number} The hyperbolic tangent of x.
   */
  var polyfill = function(x) {
    x = Number(x);
    if (x === 0) return x;
    // Ensure exponent is negative to prevent overflow.
    var y = Math.exp(-2 * Math.abs(x));
    var z = (1 - y) / (1 + y);
    return x < 0 ? -z : z;
  };

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