MatrixInverse.cpp

Author: lxylxy123456

MatrixInverse.cpp

@@ -0,0 +1,64 @@
+//  
+//  algorithm - some algorithms in "Introduction to Algorithms", third edition
+//  Copyright (C) 2018  lxylxy123456
+//  
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as
+//  published by the Free Software Foundation, either version 3 of the
+//  License, or (at your option) any later version.
+//  
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//  
+//  You should have received a copy of the GNU Affero General Public License
+//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//  
+
+#ifndef MAIN
+#define MAIN
+#define MAIN_MatrixInverse
+#endif
+
+#ifndef FUNC_MatrixInverse
+#define FUNC_MatrixInverse
+
+#include "utils.h"
+
+#include "LUPSolve.cpp"
+
+template <typename T>
+Matrix<T> MatrixInverse(Matrix<T>& A) {
+	const size_t n = A.rows; 
+	Matrix<T> LU(A), ans(n, 0), b(n, 1, 0); 
+	PT pi = LUPDecomposition(LU); 
+	for (size_t i = 0; i < n; i++) {
+		b[i][0] = 1; 
+		Matrix<T> x = LUPSolve(LU, LU, pi, b); 
+		ans = ans.concat_h(x); 
+		b[i][0] = 0; 
+	}
+	return ans; 
+}
+#endif
+
+#ifdef MAIN_MatrixInverse
+int main(int argc, char *argv[]) {
+	const size_t n = get_argv(argc, argv, 1, 6); 
+	std::vector<int> int_a, int_b; 
+	random_integers(int_a, -n, n, n * n); 
+	using T = double; 
+	std::vector<T> buf_a(n * n), buf_b(n); 
+	for (size_t i = 0; i < int_a.size(); i++)
+		buf_a[i] = int_a[i]; 
+	Matrix<T> A(n, n, buf_a); 
+	std::cout << A << std::endl; 
+	Matrix<T> B = MatrixInverse(A); 
+	std::cout << B << std::endl; 
+	Matrix<T> C = SquareMatrixMultiply(A, B, (T) 0); 
+	std::cout << C << std::endl; 
+	return 0; 
+}
+#endif
+

README.md

@@ -187,6 +187,7 @@
 | 28 | LUPSolve.cpp					| LUP Solve								|  817 |
 | 28 | LUPSolve.cpp					| LU Decomposition						|  821 |
 | 28 | LUPSolve.cpp					| LUP Decomposition						|  824 |
+| 28 | MatrixInverse.cpp			| Matrix Inverse						|  828 |
 
 # Supplementary Files
 * `utils.h`: Utils