time-to-botec

Benchmark sampling in different programming languages
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cosm1.js (2183B)

      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 * ## Notice
     20 *
     21 * The original C code, long comment, copyright, license, and constants are from [Cephes]{@link http://www.netlib.org/cephes}. The implementation follows the original, but has been modified for JavaScript.
     22 *
     23 * ```text
     24 * Copyright 2000 by Stephen L. Moshier
     25 *
     26 * Some software in this archive may be from the book _Methods and Programs for Mathematical Functions_ (Prentice-Hall or Simon & Schuster International, 1989) or from the Cephes Mathematical Library, a commercial product. In either event, it is copyrighted by the author. What you see here may be used freely but it comes with no support or guarantee.
     27 *
     28 * Stephen L. Moshier
     29 * moshier@na-net.ornl.gov
     30 * ```
     31 */
     32 
     33 'use strict';
     34 
     35 // MODULES //
     36 
     37 var cos = require( './../../../../base/special/cos' );
     38 var polyval = require( './polyval_p.js' );
     39 
     40 
     41 // VARIABLES //
     42 
     43 var PIO4 = 7.85398163397448309616e-1; // 4/π
     44 
     45 
     46 // MAIN //
     47 
     48 /**
     49 * Computes the cosine of a number minus one.
     50 *
     51 * @param {number} x - input value (in radians)
     52 * @returns {number} cosine minus one
     53 *
     54 * @example
     55 * var v = cosm1( 0.0 );
     56 * // returns 0.0
     57 *
     58 * @example
     59 * var PI = require( '@stdlib/constants/float64/pi' );
     60 *
     61 * var v = cosm1( PI/4.0 );
     62 * // returns ~-0.293
     63 *
     64 * @example
     65 * var PI = require( '@stdlib/constants/float64/pi' );
     66 *
     67 * var v = cosm1( -PI/6.0 );
     68 * // returns ~-0.134
     69 *
     70 * @example
     71 * var v = cosm1( NaN );
     72 * // returns NaN
     73 */
     74 function cosm1( x ) {
     75 	var x2;
     76 	if ( x < -PIO4 || x > PIO4 ) {
     77 		return cos( x ) - 1.0;
     78 	}
     79 	x2 = x * x;
     80 	return ( -0.5*x2 ) + ( x2*x2*polyval( x2 ) );
     81 }
     82 
     83 
     84 // EXPORTS //
     85 
     86 module.exports = cosm1;