time-to-botec

Benchmark sampling in different programming languages
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y_is_infinite.js (2048B)

      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 abs = require( './../../../../base/special/abs' );
     24 var PINF = require( '@stdlib/constants/float64/pinf' );
     25 
     26 
     27 // MAIN //
     28 
     29 /**
     30 * Evaluates the exponential function when \\( y = \pm \infty\\).
     31 *
     32 * @private
     33 * @param {number} x - base
     34 * @param {number} y - exponent
     35 * @returns {number} function value
     36 *
     37 * @example
     38 * var v = pow( -1.0, Infinity );
     39 * // returns NaN
     40 *
     41 * @example
     42 * var v = pow( -1.0, -Infinity  );
     43 * // returns NaN
     44 *
     45 * @example
     46 * var v = pow( 1.0, Infinity );
     47 * // returns 1.0
     48 *
     49 * @example
     50 * var v = pow( 1.0, -Infinity  );
     51 * // returns 1.0
     52 *
     53 * @example
     54 * var v = pow( 0.5, Infinity );
     55 * // returns 0.0
     56 *
     57 * @example
     58 * var v = pow( 0.5, -Infinity  );
     59 * // returns Infinity
     60 *
     61 * @example
     62 * var v = pow( 1.5, -Infinity  );
     63 * // returns 0.0
     64 *
     65 * @example
     66 * var v = pow( 1.5, Infinity );
     67 * // returns Infinity
     68 */
     69 function pow( x, y ) {
     70 	if ( x === -1.0 ) {
     71 		// Julia (0.4.2) and Python (2.7.9) return `1.0` (WTF???). JavaScript (`Math.pow`), R, and libm return `NaN`. We choose `NaN`, as the value is indeterminate; i.e., we cannot determine whether `y` is odd, even, or somewhere in between.
     72 		return (x-x)/(x-x); // signal NaN
     73 	}
     74 	if ( x === 1.0 ) {
     75 		return 1.0;
     76 	}
     77 	// (|x| > 1 && y === NINF) || (|x| < 1 && y === PINF)
     78 	if ( (abs(x) < 1.0) === (y === PINF) ) {
     79 		return 0.0;
     80 	}
     81 	// (|x| > 1 && y === PINF) || (|x| < 1 && y === NINF)
     82 	return PINF;
     83 }
     84 
     85 
     86 // EXPORTS //
     87 
     88 module.exports = pow;