time-to-botec

Benchmark sampling in different programming languages
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main.js (3885B)

      1 /**
      2 * @license Apache-2.0
      3 *
      4 * Copyright (c) 2020 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 sqrt = require( './../../../../base/special/sqrt' );
     24 var floor = require( './../../../../base/special/floor' );
     25 var FLOAT64_MAX_SAFE_INTEGER = require( '@stdlib/constants/float64/max-safe-integer' );
     26 var WHEEL_PRIMES = require( './wheel_primes.json' );
     27 
     28 
     29 // MAIN //
     30 
     31 /**
     32 * Returns a boolean indicating whether a number is a prime.
     33 *
     34 * @param {number} x - value to test
     35 * @returns {boolean} boolean indicating whether a value is a prime number
     36 *
     37 * @example
     38 * var bool = isPrime( 5.0 );
     39 * // returns true
     40 *
     41 * @example
     42 * var bool = isPrime( 4.0 );
     43 * // returns false
     44 */
     45 function isPrime( x ) {
     46 	var N;
     47 	var i;
     48 
     49 	// Check whether the number is an integer...
     50 	if ( floor( x ) !== x ) {
     51 		return false;
     52 	}
     53 	// Check whether the number is positive...
     54 	if ( x <= 3 ) {
     55 		return (x > 1); // primes: 2, 3
     56 	}
     57 	// Check whether the number is even...
     58 	if ( x > FLOAT64_MAX_SAFE_INTEGER || x%2 === 0 ) {
     59 		return false;
     60 	}
     61 	// Check for small primes...
     62 	if ( x < 9 ) {
     63 		return true; // primes: 5, 7
     64 	}
     65 	// Check whether the number is evenly divisible by `3`...
     66 	if ( x%3 === 0 ) {
     67 		return false;
     68 	}
     69 	// Check whether the number is evenly divisible by `5`...
     70 	if ( x%5 === 0 ) {
     71 		return false;
     72 	}
     73 	// Check whether the number is evenly divisible by `7`...
     74 	if ( x%7 === 0 ) {
     75 		return false;
     76 	}
     77 	// Check whether the number is a prime number in the wheel...
     78 	if ( WHEEL_PRIMES[ x ] ) {
     79 		return true;
     80 	}
     81 	// Use trial division (with wheel factorization; see https://en.wikipedia.org/wiki/Wheel_factorization) to detect composite numbers, leveraging the fact that all primes greater than `210` are of the form `210k±1`...
     82 	N = floor( sqrt( x ) );
     83 	for ( i = 11; i <= N; i += 210 ) {
     84 		if (
     85 			x%i === 0 ||       // 11
     86 			x%(i+2) === 0 ||   // 13
     87 			x%(i+6) === 0 ||   // 17
     88 			x%(i+8) === 0 ||   // 19
     89 			x%(i+12) === 0 ||  // 23
     90 			x%(i+18) === 0 ||  // 29
     91 			x%(i+20) === 0 ||  // 31
     92 			x%(i+26) === 0 ||  // 37
     93 			x%(i+30) === 0 ||  // 41
     94 			x%(i+32) === 0 ||  // 43
     95 			x%(i+36) === 0 ||  // 47
     96 			x%(i+42) === 0 ||  // 53
     97 			x%(i+48) === 0 ||  // 59
     98 			x%(i+50) === 0 ||  // 61
     99 			x%(i+56) === 0 ||  // 67
    100 			x%(i+60) === 0 ||  // 71
    101 			x%(i+62) === 0 ||  // 73
    102 			x%(i+68) === 0 ||  // 79
    103 			x%(i+72) === 0 ||  // 83
    104 			x%(i+78) === 0 ||  // 89
    105 			x%(i+86) === 0 ||  // 97
    106 			x%(i+90) === 0 ||  // 101
    107 			x%(i+92) === 0 ||  // 103
    108 			x%(i+96) === 0 ||  // 107
    109 			x%(i+98) === 0 ||  // 109
    110 			x%(i+102) === 0 || // 113
    111 			x%(i+110) === 0 || // 121 (relatively prime)
    112 			x%(i+116) === 0 || // 127
    113 			x%(i+120) === 0 || // 131
    114 			x%(i+126) === 0 || // 137
    115 			x%(i+128) === 0 || // 139
    116 			x%(i+132) === 0 || // 143 (relatively prime)
    117 			x%(i+138) === 0 || // 149
    118 			x%(i+140) === 0 || // 151
    119 			x%(i+146) === 0 || // 157
    120 			x%(i+152) === 0 || // 163
    121 			x%(i+156) === 0 || // 167
    122 			x%(i+158) === 0 || // 169 (relatively prime)
    123 			x%(i+162) === 0 || // 173
    124 			x%(i+168) === 0 || // 179
    125 			x%(i+170) === 0 || // 181
    126 			x%(i+176) === 0 || // 187 (relatively prime)
    127 			x%(i+180) === 0 || // 191
    128 			x%(i+182) === 0 || // 193
    129 			x%(i+186) === 0 || // 197
    130 			x%(i+188) === 0 || // 199
    131 			x%(i+198) === 0 || // 209 (relatively prime)
    132 			x%(i+200) === 0    // 211
    133 		) {
    134 			return false;
    135 		}
    136 	}
    137 	return true;
    138 }
    139 
    140 
    141 // EXPORTS //
    142 
    143 module.exports = isPrime;