| // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| import "package:expect/expect.dart"; |
| |
| import "dart:math" show pow; |
| |
| var smallNumber = 1234567890; // is 31-bit integer. |
| var mediumNumber = 1234567890123456; // is 53-bit integer |
| |
| testModPow() { |
| test(x, e, m, expectedResult) { |
| // Check that expected result is correct, using an unoptimized version. |
| assert(() { |
| if (1 is double) return true; // Don't have bignums. |
| slowModPow(x, e, m) { |
| var r = 1; |
| while (e > 0) { |
| if (e.isOdd) r = (r * x) % m; |
| e >>= 1; |
| x = (x * x) % m; |
| } |
| return r; |
| } |
| |
| return slowModPow(x, e, m) == expectedResult; |
| }()); |
| var result = x.modPow(e, m); |
| Expect.equals(expectedResult, result, "$x.modPow($e, $m)"); |
| } |
| |
| test(10, 20, 1, 0); |
| test(1234567890, 1000000001, 19, 11); |
| test(1234567890, 19, 1000000001, 122998977); |
| test(19, 1234567890, 1000000001, 619059596); |
| test(19, 1000000001, 1234567890, 84910879); |
| test(1000000001, 19, 1234567890, 872984351); |
| test(1000000001, 1234567890, 19, 0); |
| } |
| |
| testModInverse() { |
| test(x, m, expectedResult) { |
| //print("$x op $m == $expectedResult"); |
| // Check that expectedResult is an inverse. |
| assert(expectedResult < m); |
| // The 1 % m handles the m = 1 special case. |
| // This test may overflow if we don't have bignums, so only run on VM. |
| assert(1 is double || (((x % m) * expectedResult) - 1) % m == 0); |
| |
| var result = x.modInverse(m); |
| Expect.equals(expectedResult, result, "$x modinv $m"); |
| |
| if (x > m) { |
| x = x % m; |
| var result = x.modInverse(m); |
| Expect.equals(expectedResult, result, "$x modinv $m"); |
| } |
| } |
| |
| testThrows(x, m) { |
| // Throws if not co-prime, which is a symmetric property. |
| Expect.throws(() => x.modInverse(m), null, "$x modinv $m"); |
| Expect.throws(() => m.modInverse(x), null, "$m modinv $x"); |
| } |
| |
| test(1, 1, 0); |
| |
| testThrows(0, 1000000001); |
| testThrows(2, 4); |
| testThrows(99, 9); |
| testThrows(19, 1000000001); |
| |
| // Co-prime numbers |
| test(1234567890, 19, 11); |
| test(1234567890, 1000000001, 189108911); |
| test(19, 1234567890, 519818059); |
| test(1000000001, 1234567890, 1001100101); |
| |
| test(12345, 12346, 12345); |
| test(12345, 12346, 12345); |
| |
| test(smallNumber, 137, 42); |
| test(137, smallNumber, 856087223); |
| test(mediumNumber, 137, 77); |
| test(137, mediumNumber, 540686667207353); |
| } |
| |
| testGcd() { |
| // Call testFunc with all combinations and orders of plus/minus |
| // value and other. |
| callCombos(value, other, testFunc) { |
| testFunc(value, other); |
| testFunc(value, -other); |
| testFunc(-value, other); |
| testFunc(-value, -other); |
| if (value == other) return; |
| testFunc(other, value); |
| testFunc(other, -value); |
| testFunc(-other, value); |
| testFunc(-other, -value); |
| } |
| |
| // Test that gcd of value and other (non-negative) is expectedResult. |
| // Tests all combinations of positive and negative values and order of |
| // operands, so use positive values and order is not important. |
| test(value, other, expectedResult) { |
| // Check for bug in test. |
| assert(expectedResult == 0 || value % expectedResult == 0); |
| assert(expectedResult == 0 || other % expectedResult == 0); |
| callCombos(value, other, (a, b) { |
| var result = a.gcd(b); |
| |
| /// Check that the result is a divisor. |
| Expect.equals(0, result == 0 ? a : a % result, "$result | $a"); |
| Expect.equals(0, result == 0 ? b : b % result, "$result | $b"); |
| // Check for bug in test. If assert fails, the expected value is too low, |
| // and the gcd call has found a greater common divisor. |
| assert(result >= expectedResult); |
| Expect.equals(expectedResult, result, "$a.gcd($b)"); |
| }); |
| } |
| |
| // Test that gcd of value and other (non-negative) throws. |
| testThrows(value, other) { |
| callCombos(value, other, (a, b) { |
| Expect.throws(() => a.gcd(b), null, "$a.gcd($b)"); |
| }); |
| } |
| |
| testThrows(2.5, 5); // Not a method on double. |
| testThrows(5, 2.5); // Not accepting non-int arguments. |
| |
| // Format: |
| // test(value1, value2, expectedResult); |
| test(1, 1, 1); // both are 1 |
| test(1, 2, 1); // one is 1 |
| test(3, 5, 1); // coprime. |
| test(37, 37, 37); // Same larger prime. |
| |
| test(9999, 7272, 909); // Larger numbers |
| |
| test(0, 1000, 1000); // One operand is zero. |
| test(0, 0, 0); // Both operands are zero. |
| |
| // Multiplying both operands by a number multiplies result by same number. |
| test(693, 609, 21); |
| test(693 << 5, 609 << 5, 21 << 5); |
| test(693 * 937, 609 * 937, 21 * 937); |
| test(693 * pow(2, 32), 609 * pow(2, 32), 21 * pow(2, 32)); |
| test(693 * pow(2, 52), 609 * pow(2, 52), 21 * pow(2, 52)); |
| test(693 * pow(2, 53), 609 * pow(2, 53), 21 * pow(2, 53)); // Regression. |
| test(693 * pow(2, 99), 609 * pow(2, 99), 21 * pow(2, 99)); |
| |
| test(1234567890, 19, 1); |
| test(1234567890, 1000000001, 1); |
| test(19, 1000000001, 19); |
| |
| test(0x3FFFFFFF, 0x3FFFFFFF, 0x3FFFFFFF); |
| test(0x3FFFFFFF, 0x40000000, 1); |
| |
| test(pow(2, 54), pow(2, 53), pow(2, 53)); |
| |
| test((pow(2, 52) - 1) * pow(2, 10), (pow(2, 26) - 1) * pow(2, 22), |
| (pow(2, 26) - 1) * pow(2, 10)); |
| } |
| |
| main() { |
| testModPow(); // //# modPow: ok |
| testModInverse(); |
| testGcd(); |
| } |