time-to-botec

Benchmark sampling in different programming languages
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      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 1985, 1995, 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 evalpoly = require( './../../../../../base/tools/evalpoly' ).factory; // TODO: replace with compiled polyval functions
     38 var floor = require( './../../../../../base/special/floor' );
     39 var ldexp = require( './../../../../../base/special/ldexp' );
     40 var isnan = require( './../../../../../base/assert/is-nan' );
     41 var isinfinite = require( './../../../../../base/assert/is-infinite' );
     42 
     43 
     44 // VARIABLES //
     45 
     46 var DP1 = 7.85398125648498535156e-1; // 0x3fe921fb40000000, Pi/4 split into three parts
     47 var DP2 = 3.77489470793079817668e-8; // 0x3e64442d00000000,
     48 var DP3 = 2.69515142907905952645e-15; // 0x3ce8469898cc5170,
     49 var PIO4 = 7.85398163397448309616E-1; // 4/pi
     50 var SIN_COEF = [
     51 	-1.66666666666666307295e-1, // 0xbfc5555555555548
     52 	8.33333333332211858878e-3, // 0x3f8111111110f7d0
     53 	-1.98412698295895385996e-4, // 0xbf2a01a019bfdf03
     54 	2.75573136213857245213e-6, // 0x3ec71de3567d48a1
     55 	-2.50507477628578072866e-8, // 0xbe5ae5e5a9291f5d
     56 	1.58962301576546568060e-10 // 0x3de5d8fd1fd19ccd
     57 ];
     58 var COS_COEF = [
     59 	4.16666666666665929218e-2, // 0x3fa555555555554b
     60 	-1.38888888888730564116e-3, // 0xbf56c16c16c14f91
     61 	2.48015872888517045348e-5, // 0x3efa01a019c844f5
     62 	-2.75573141792967388112e-7, // 0xbe927e4f7eac4bc6
     63 	2.08757008419747316778e-9, // 0x3e21ee9d7b4e3f05
     64 	-1.13585365213876817300e-11 // 0xbda8fa49a0861a9b
     65 ];
     66 
     67 
     68 // FUNCTIONS //
     69 
     70 // Compile functions to evaluate polynomial functions based on the above coefficients...
     71 var polyvalSIN = evalpoly( SIN_COEF );
     72 var polyvalCOS = evalpoly( COS_COEF );
     73 
     74 
     75 // MAIN //
     76 
     77 /**
     78 * Computes the cosine of a number.
     79 *
     80 * @param {number} x - input value
     81 * @returns {number} cosine (in radians)
     82 *
     83 * @example
     84 * var v = cos( 0.0 );
     85 * // returns 1.0
     86 *
     87 * @example
     88 * var v = cos( 3.14/4.0 );
     89 * // returns ~0.707
     90 *
     91 * @example
     92 * var v = cos( -3.14/6.0 );
     93 * // returns ~0.866
     94 *
     95 * @example
     96 * var v = cos( NaN );
     97 * // returns NaN
     98 */
     99 function cos( x ) {
    100 	var sgn;
    101 	var zz;
    102 	var i;
    103 	var j;
    104 	var y;
    105 	var z;
    106 
    107 	if ( isnan( x ) || isinfinite( x ) ) {
    108 		return NaN;
    109 	}
    110 
    111 	// Make argument positive...
    112 	sgn = 1;
    113 	if ( x < 0 ) {
    114 		x = -x;
    115 	}
    116 
    117 	y = floor( x/PIO4 );
    118 	z = ldexp( y, -4 );
    119 	z = floor( z ); // Integer part of y/8
    120 	z = y - ldexp( z, 4 ); // y - 16 * (y/16)
    121 
    122 	// Integer and fractional part modulo one octant...
    123 	i = y;
    124 
    125 	// Map zeros to origin...
    126 	if ( i & 1 ) {
    127 		i += 1;
    128 		y += 1.0;
    129 	}
    130 	j = i & 7;
    131 	if ( j > 3 ) {
    132 		j -= 4;
    133 		sgn = -sgn;
    134 	}
    135 	if ( j > 1 ) {
    136 		sgn = -sgn;
    137 	}
    138 
    139 	// Extended precision modular arithmetic...
    140 	z = ( ( x - ( y*DP1 ) ) - ( y*DP2 ) ) - ( y * DP3 );
    141 	zz = z * z;
    142 
    143 	if ( j === 1 || j === 2 ) {
    144 		y = z + ( z * z * z * polyvalSIN( zz ) );
    145 	} else {
    146 		y = 1.0 - ldexp( zz, -1 ) + ( zz * zz * polyvalCOS( zz ) );
    147 	}
    148 
    149 	if ( sgn < 0 ) {
    150 		y = -y;
    151 	}
    152 	return y;
    153 }
    154 
    155 
    156 // EXPORTS //
    157 
    158 module.exports = cos;