time-to-botec

Benchmark sampling in different programming languages
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sinpx.js (2055B)

      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 and copyright notice are from the [Boost library]{@link http://www.boost.org/doc/libs/1_64_0/boost/math/special_functions/gamma.hpp}. The implementation has been modified for JavaScript.
     22 *
     23 * ```text
     24 * Copyright John Maddock 2006-7, 2013-14.
     25 * Copyright Paul A. Bristow 2007, 2013-14.
     26 * Copyright Nikhar Agrawal 2013-14.
     27 * Copyright Christopher Kormanyos 2013-14.
     28 *
     29 * Use, modification and distribution are subject to the
     30 * Boost Software License, Version 1.0. (See accompanying file
     31 * LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
     32 * ```
     33 */
     34 
     35 'use strict';
     36 
     37 // TODO: consider moving this to a separate pkg: @stdlib/math/base/special/xsinpi
     38 
     39 // MODULES //
     40 
     41 var isOdd = require( './../../../../../base/assert/is-odd' );
     42 var floor = require( './../../../../../base/special/floor' );
     43 var sinpi = require( './../../../../../base/special/sinpi' );
     44 
     45 
     46 // MAIN //
     47 
     48 /**
     49 * Calculates `x * sin(pi * x)`, taking extra care near when `x` is near a whole number.
     50 *
     51 * @private
     52 * @param {number} x - input value
     53 * @returns {number} function value
     54 */
     55 function sinpx( x ) {
     56 	var result;
     57 	var dist;
     58 	var sign;
     59 	var fl;
     60 
     61 	sign = 1;
     62 	if ( x < 0.0 ) {
     63 		x = -x;
     64 	}
     65 	fl = floor( x );
     66 	if ( isOdd(fl) ) {
     67 		fl += 1;
     68 		dist = fl - x;
     69 		sign = -sign;
     70 	} else {
     71 		dist = x - fl;
     72 	}
     73 	if ( dist > 0.5 ) {
     74 		dist = 1.0 - dist;
     75 	}
     76 	result = sinpi( dist );
     77 	return sign*x*result;
     78 }
     79 
     80 
     81 // EXPORTS //
     82 
     83 module.exports = sinpx;