|
| 1 | +/** |
| 2 | + * @file |
| 3 | + * @brief [A babylonian method |
| 4 | + * (BM)](https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method) |
| 5 | + * is an algorithm that computes the square root. |
| 6 | + * @details |
| 7 | + * This algorithm has an application in use case scenario where a user wants |
| 8 | + * find accurate square roots of large numbers |
| 9 | + * @author [Ameya Chawla](https://github.com/ameyachawlaggsipu) |
| 10 | + */ |
| 11 | + |
| 12 | +#include <cassert> /// for assert |
| 13 | +#include <iostream> /// for IO operations |
| 14 | + |
| 15 | +#include "math.h" |
| 16 | + |
| 17 | +/** |
| 18 | + * @namespace numerical_methods |
| 19 | + * @brief Numerical algorithms/methods |
| 20 | + */ |
| 21 | + |
| 22 | +namespace numerical_methods { |
| 23 | + |
| 24 | +/** |
| 25 | + * @brief Babylonian methods is an iterative function which returns |
| 26 | + * square root of radicand |
| 27 | + * @param radicand is the radicand |
| 28 | + * @returns x1 the square root of radicand |
| 29 | + */ |
| 30 | + |
| 31 | +double babylonian_method(double radicand) { |
| 32 | + int i = 1; /// To find initial root or rough approximation |
| 33 | + |
| 34 | + while (i * i <= radicand) { |
| 35 | + i++; |
| 36 | + } |
| 37 | + |
| 38 | + i--; /// Real Initial value will be i-1 as loop stops on +1 value |
| 39 | + |
| 40 | + double x0 = i; /// Storing previous value for comparison |
| 41 | + double x1 = |
| 42 | + (radicand / x0 + x0) / 2; /// Storing calculated value for comparison |
| 43 | + double temp = NAN; /// Temp variable to x0 and x1 |
| 44 | + |
| 45 | + while (std::max(x0, x1) - std::min(x0, x1) < 0.0001) { |
| 46 | + temp = (radicand / x1 + x1) / 2; /// Newly calculated root |
| 47 | + x0 = x1; |
| 48 | + x1 = temp; |
| 49 | + } |
| 50 | + |
| 51 | + return x1; /// Returning final root |
| 52 | +} |
| 53 | + |
| 54 | +} // namespace numerical_methods |
| 55 | + |
| 56 | +/** |
| 57 | + * @brief Self-test implementations |
| 58 | + * @details |
| 59 | + * Declaring two test cases and checking for the error |
| 60 | + * in predicted and true value is less than 0.0001. |
| 61 | + * @returns void |
| 62 | + */ |
| 63 | +static void test() { |
| 64 | + /* descriptions of the following test */ |
| 65 | + |
| 66 | + auto testcase1 = 125348; /// Testcase 1 |
| 67 | + auto testcase2 = 752080; /// Testcase 2 |
| 68 | + |
| 69 | + auto real_output1 = 354.045194855; /// Real Output 1 |
| 70 | + auto real_output2 = 867.225460881; /// Real Output 2 |
| 71 | + |
| 72 | + auto test_result1 = numerical_methods::babylonian_method(testcase1); |
| 73 | + /// Test result for testcase 1 |
| 74 | + auto test_result2 = numerical_methods::babylonian_method(testcase2); |
| 75 | + /// Test result for testcase 2 |
| 76 | + |
| 77 | + assert(std::max(test_result1, real_output1) - |
| 78 | + std::min(test_result1, real_output1) < |
| 79 | + 0.0001); |
| 80 | + /// Testing for test Case 1 |
| 81 | + assert(std::max(test_result2, real_output2) - |
| 82 | + std::min(test_result2, real_output2) < |
| 83 | + 0.0001); |
| 84 | + /// Testing for test Case 2 |
| 85 | + |
| 86 | + std::cout << "All tests have successfully passed!\n"; |
| 87 | +} |
| 88 | + |
| 89 | +/** |
| 90 | + * @brief Main function |
| 91 | + * @param argc commandline argument count (ignored) |
| 92 | + * @param argv commandline array of arguments (ignored) |
| 93 | + * calls automated test function to test the working of fast fourier transform. |
| 94 | + * @returns 0 on exit |
| 95 | + */ |
| 96 | + |
| 97 | +int main(int argc, char const *argv[]) { |
| 98 | + test(); // run self-test implementations |
| 99 | + // with 2 defined test cases |
| 100 | + return 0; |
| 101 | +} |
0 commit comments