Added LU Decomposition Algorithm for matrix (#6834)

* Added LU decomposition algorthm * Added LU decomposition algorthim * Added LU decomposition algorthim * Added LU decomposition algorthim * Added LU decomposition algorthim * Added LU decomposition algorthim * Added LU decomposition algorthim * Added LU decomposition algorthim * Added LU decomposition algorthim
2025-12-19 07:00:35 +08:00 · 2025-11-04 02:59:44 +05:30
parent 82ff14c36e
commit 100462d8e9
2 changed files with 128 additions and 0 deletions
--- a/src/test/java/com/thealgorithms/matrix/LUDecompositionTest.java
+++ b/src/test/java/com/thealgorithms/matrix/LUDecompositionTest.java
@@ -0,0 +1,40 @@
+package com.thealgorithms.matrix;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class LUDecompositionTest {
+
+    @Test
+    public void testLUDecomposition() {
+        double[][] a = {{4, 3}, {6, 3}};
+
+        // Perform LU decomposition
+        LUDecomposition.LU lu = LUDecomposition.decompose(a);
+        double[][] l = lu.l;
+        double[][] u = lu.u;
+
+        // Reconstruct a from l and u
+        double[][] reconstructed = multiplyMatrices(l, u);
+
+        // Assert that reconstructed matrix matches original a
+        for (int i = 0; i < a.length; i++) {
+            assertArrayEquals(a[i], reconstructed[i], 1e-9);
+        }
+    }
+
+    // Helper method to multiply two matrices
+    private double[][] multiplyMatrices(double[][] a, double[][] b) {
+        int n = a.length;
+        double[][] c = new double[n][n];
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                for (int k = 0; k < n; k++) {
+                    c[i][j] += a[i][k] * b[k][j];
+                }
+            }
+        }
+        return c;
+    }
+}