time-to-botec

Benchmark sampling in different programming languages
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floorsd.js (2756B)

      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 isnan = require( './../../../../base/assert/is-nan' );
     24 var isInfinite = require( './../../../../base/assert/is-infinite' );
     25 var pow = require( './../../../../base/special/pow' );
     26 var log10 = require( './../../../../base/special/log10' );
     27 var ln = require( './../../../../base/special/ln' );
     28 var abs = require( './../../../../base/special/abs' );
     29 var floor = require( './../../../../base/special/floor' );
     30 var exponent = require( '@stdlib/number/float64/base/exponent' );
     31 
     32 
     33 // MAIN //
     34 
     35 /**
     36 * Rounds a numeric value to the nearest number toward negative infinity with \\(N\\) significant figures.
     37 *
     38 * @param {number} x - input value
     39 * @param {PositiveInteger} n - number of significant figures
     40 * @param {PositiveInteger} [b=10] - base
     41 * @returns {number} rounded value
     42 *
     43 * @example
     44 * var v = floorsd( 3.141592653589793, 5 );
     45 * // returns 3.1415
     46 *
     47 * @example
     48 * var v = floorsd( 3.141592653589793, 1 );
     49 * // returns 3.0
     50 *
     51 * @example
     52 * var v = floorsd( 12368.0, 2 );
     53 * // returns 12000.0
     54 *
     55 * @example
     56 * var v = floorsd( 0.0313, 2, 2 );
     57 * // returns 0.03125
     58 */
     59 function floorsd( x, n, b ) {
     60 	var base;
     61 	var exp;
     62 	var s;
     63 	var y;
     64 	if (
     65 		isnan( x ) ||
     66 		isnan( n ) ||
     67 		n < 1 ||
     68 		isInfinite( n )
     69 	) {
     70 		return NaN;
     71 	}
     72 	if ( arguments.length > 2 ) {
     73 		if (
     74 			isnan( b ) ||
     75 			b <= 0 ||
     76 			isInfinite( b )
     77 		) {
     78 			return NaN;
     79 		}
     80 		base = b;
     81 	} else {
     82 		base = 10;
     83 	}
     84 	if ( isInfinite( x ) || x === 0.0 ) {
     85 		return x;
     86 	}
     87 	if ( base === 10 ) {
     88 		exp = log10( abs( x ) );
     89 	}
     90 	else if ( base === 2 ) {
     91 		exp = exponent( abs( x ) );
     92 	}
     93 	else {
     94 		exp = ln( abs(x) ) / ln( base );
     95 	}
     96 	exp = floor( exp - n + 1.0 );
     97 	s = pow( base, abs( exp ) );
     98 
     99 	// Check for overflow:
    100 	if ( isInfinite( s ) ) {
    101 		return x;
    102 	}
    103 	// To avoid numerical stability issues due to floating-point rounding error (e.g., 3.55/0.1-35.5 = -7.105427357601e-15 and 3.55*10-35.5 = 0), we must treat positive and negative exponents separately.
    104 	if ( exp < 0 ) {
    105 		y = floor( x * s ) / s;
    106 	} else {
    107 		y = floor( x / s ) * s;
    108 	}
    109 	// Check for overflow:
    110 	if ( isInfinite( y ) ) {
    111 		return x;
    112 	}
    113 	return y;
    114 }
    115 
    116 
    117 // EXPORTS //
    118 
    119 module.exports = floorsd;