isPrime.js 3.8 KB

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  1. import { deepMap } from '../../utils/collection.js';
  2. import { factory } from '../../utils/factory.js';
  3. var name = 'isPrime';
  4. var dependencies = ['typed'];
  5. export var createIsPrime = /* #__PURE__ */factory(name, dependencies, _ref => {
  6. var {
  7. typed
  8. } = _ref;
  9. /**
  10. * Test whether a value is prime: has no divisors other than itself and one.
  11. * The function supports type `number`, `bignumber`.
  12. *
  13. * The function is evaluated element-wise in case of Array or Matrix input.
  14. *
  15. * Syntax:
  16. *
  17. * math.isPrime(x)
  18. *
  19. * Examples:
  20. *
  21. * math.isPrime(3) // returns true
  22. * math.isPrime(-2) // returns false
  23. * math.isPrime(0) // returns false
  24. * math.isPrime(-0) // returns false
  25. * math.isPrime(0.5) // returns false
  26. * math.isPrime('2') // returns true
  27. * math.isPrime([2, 17, 100]) // returns [true, true, false]
  28. *
  29. * See also:
  30. *
  31. * isNumeric, isZero, isNegative, isInteger
  32. *
  33. * @param {number | BigNumber | Array | Matrix} x Value to be tested
  34. * @return {boolean} Returns true when `x` is larger than zero.
  35. * Throws an error in case of an unknown data type.
  36. */
  37. return typed(name, {
  38. number: function number(x) {
  39. if (x * 0 !== 0) {
  40. return false;
  41. }
  42. if (x <= 3) {
  43. return x > 1;
  44. }
  45. if (x % 2 === 0 || x % 3 === 0) {
  46. return false;
  47. }
  48. for (var i = 5; i * i <= x; i += 6) {
  49. if (x % i === 0 || x % (i + 2) === 0) {
  50. return false;
  51. }
  52. }
  53. return true;
  54. },
  55. BigNumber: function BigNumber(n) {
  56. if (n.toNumber() * 0 !== 0) {
  57. return false;
  58. }
  59. if (n.lte(3)) return n.gt(1);
  60. if (n.mod(2).eq(0) || n.mod(3).eq(0)) return false;
  61. if (n.lt(Math.pow(2, 32))) {
  62. var x = n.toNumber();
  63. for (var i = 5; i * i <= x; i += 6) {
  64. if (x % i === 0 || x % (i + 2) === 0) {
  65. return false;
  66. }
  67. }
  68. return true;
  69. }
  70. function modPow(base, exponent, modulus) {
  71. // exponent can be huge, use non-recursive variant
  72. var accumulator = 1;
  73. while (!exponent.eq(0)) {
  74. if (exponent.mod(2).eq(0)) {
  75. exponent = exponent.div(2);
  76. base = base.mul(base).mod(modulus);
  77. } else {
  78. exponent = exponent.sub(1);
  79. accumulator = base.mul(accumulator).mod(modulus);
  80. }
  81. }
  82. return accumulator;
  83. }
  84. // https://en.wikipedia.org/wiki/Miller%E2%80%93Rabin_primality_test#Deterministic_variants
  85. var Decimal = n.constructor.clone({
  86. precision: n.toFixed(0).length * 2
  87. });
  88. n = new Decimal(n);
  89. var r = 0;
  90. var d = n.sub(1);
  91. while (d.mod(2).eq(0)) {
  92. d = d.div(2);
  93. r += 1;
  94. }
  95. var bases = null;
  96. // https://en.wikipedia.org/wiki/Miller–Rabin_primality_test#Testing_against_small_sets_of_bases
  97. if (n.lt('3317044064679887385961981')) {
  98. bases = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41].filter(x => x < n);
  99. } else {
  100. var max = Math.min(n.toNumber() - 2, Math.floor(2 * Math.pow(n.toFixed(0).length * Math.log(10), 2)));
  101. bases = [];
  102. for (var _i = 2; _i <= max; _i += 1) {
  103. bases.push(max);
  104. }
  105. }
  106. for (var _i2 = 0; _i2 < bases.length; _i2 += 1) {
  107. var a = bases[_i2];
  108. var adn = modPow(n.sub(n).add(a), d, n);
  109. if (!adn.eq(1)) {
  110. for (var _i3 = 0, _x = adn; !_x.eq(n.sub(1)); _i3 += 1, _x = _x.mul(_x).mod(n)) {
  111. if (_i3 === r - 1) {
  112. return false;
  113. }
  114. }
  115. }
  116. }
  117. return true;
  118. },
  119. 'Array | Matrix': typed.referToSelf(self => x => deepMap(x, self))
  120. });
  121. });