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91 lines
2.5 KiB
C++
91 lines
2.5 KiB
C++
/**
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* \file
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* \brief [LU decomposition](https://en.wikipedia.org/wiki/LU_decompositon) of a
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* square matrix
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* \author [Krishna Vedala](https://github.com/kvedala)
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*/
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#include <cassert>
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#include <ctime>
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#include <iomanip>
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#include <iostream>
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#include "./lu_decomposition.h"
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/**
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* operator to print a matrix
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*/
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template <typename T>
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std::ostream &operator<<(std::ostream &out, matrix<T> const &v) {
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const int width = 10;
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const char separator = ' ';
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for (size_t row = 0; row < v.size(); row++) {
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for (size_t col = 0; col < v[row].size(); col++)
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out << std::left << std::setw(width) << std::setfill(separator)
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<< v[row][col];
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out << std::endl;
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}
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return out;
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}
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/**
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* Test LU decomposition
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* \todo better ways to self-check a matrix output?
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*/
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void test1() {
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int mat_size = 3; // default matrix size
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const int range = 50;
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const int range2 = range >> 1;
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/* Create a square matrix with random values */
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matrix<double> A(mat_size, std::valarray<double>(mat_size));
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matrix<double> L(mat_size, std::valarray<double>(mat_size)); // output
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matrix<double> U(mat_size, std::valarray<double>(mat_size)); // output
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for (int i = 0; i < mat_size; i++) {
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// calloc so that all valeus are '0' by default
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for (int j = 0; j < mat_size; j++)
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/* create random values in the limits [-range2, range-1] */
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A[i][j] = static_cast<double>(std::rand() % range - range2);
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}
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std::clock_t start_t = std::clock();
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lu_decomposition(A, &L, &U);
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std::clock_t end_t = std::clock();
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std::cout << "Time taken: "
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<< static_cast<double>(end_t - start_t) / CLOCKS_PER_SEC << "\n";
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std::cout << "A = \n" << A << "\n";
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std::cout << "L = \n" << L << "\n";
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std::cout << "U = \n" << U << "\n";
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}
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/**
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* Test determinant computation using LU decomposition
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*/
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void test2() {
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std::cout << "Determinant test 1...";
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matrix<int> A1({{1, 2, 3}, {4, 9, 6}, {7, 8, 9}});
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assert(determinant_lu(A1) == -48);
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std::cout << "passed\n";
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std::cout << "Determinant test 2...";
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matrix<int> A2({{1, 2, 3}, {4, 5, 6}, {7, 8, 9}});
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assert(determinant_lu(A2) == 0);
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std::cout << "passed\n";
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std::cout << "Determinant test 3...";
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matrix<float> A3({{1.2, 2.3, 3.4}, {4.5, 5.6, 6.7}, {7.8, 8.9, 9.0}});
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assert(determinant_lu(A3) == 3.63);
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std::cout << "passed\n";
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}
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/** Main function */
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int main(int argc, char **argv) {
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std::srand(std::time(NULL)); // random number initializer
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test1();
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test2();
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return 0;
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}
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