--test file included formatting adjusted

THIRU-1074 · web-flow · commit 3aec6dc8ec03 · 2023-06-25T17:11:18.000+05:30
diff --git a/src/main/java/com/thealgorithms/maths/DeterminantOfMatrix.java b/src/main/java/com/thealgorithms/maths/DeterminantOfMatrix.java
diff --git a/src/main/java/com/thealgorithms/maths/DeterminantofMatrix.java b/src/main/java/com/thealgorithms/maths/DeterminantofMatrix.java
@@ -0,0 +1,51 @@
+package com.thealgorithms.maths;
+import java.util.*;
+/*
+ * Determinant of Matrix :https://textbooks.math.gatech.edu/ila/determinants-cofactors.html
+ */
+public class DeterminantOfMatrix {
+	public static double[][] submatrix(double[][] mat,int order,int c) {
+		//creating reference for the sub matrix
+		double[][] subMat=new double[order-1][order-1];
+		//sub_c stores the column column index of the sub matrix
+		int subC;
+		for(int i=1;i<order;i++) {	
+			//making the column count zero after each row-addition
+			subC=0;
+			for(int k=0;k<order;k++) {
+				if(k==c) {
+					continue;//skipping the column where the mat[0][c] of operation is in
+				}
+				subMat[i-1][subC]=mat[i][k];
+				subC+=1;//increasing the column count
+			}
+		}
+		return(subMat);
+	}
+	public static double determinant(double[][] mat,int order) {
+		/*determinant of the matrix with one element(order 1) :
+		 is the element itself*/
+		if (order==1) {
+			return(mat[0][0]);
+		}
+		return(operation(mat,order));
+	}
+	public static double operation(double[][] mat,int order) {
+		int check;
+		double det=0;
+		for(int c=0;c<order;++c) {
+			if(c%2==0) {
+				check=-1;
+			}
+			else {
+				check=1;
+			}
+			det+=(check*(mat[0][c])*determinant(submatrix(mat,order,c),order-1)));
+		}
+		return(det);
+	}
+}
+/*the above code will work for all square matrix whose order are greater than one.
+---to initiate this recursive algorithm pass the matrix and its order to the operation() method
+---if the order is 1 return the determinant of the matrix directly
+(determinant of the matrix with one element(order 1) :is the element itself)*/
diff --git a/src/test/java/com/thealgorithms/maths/DeterminantofMatrixTest.java b/src/test/java/com/thealgorithms/maths/DeterminantofMatrixTest.java
@@ -0,0 +1,24 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class DeterminantOfMatrixTest {
+
+    @Test
+    void testDeterminantOfMatrix() {
+        double[][] matrix1 = { { 1.0 } };
+        assertEquals(1.0, DeterminantOfMatrix.DET(matrix1, 1));
+
+        double[][] matrix2 = { { 2.0, 3.0 }, { -4.0, 5.0 } };
+        assertEquals(22.0, DeterminantOfMatrix.DET(matrix2, 2));
+
+        double[][] matrix3 = { { -1.0, 2.5, 3.0 }, { 4.0, -5.2, 6.0 }, { 7.3, -8.1, 9.6 } };
+        assertEquals(58.9, DeterminantOfMatrix.DET(matrix3, 3));
+
+        double[][] matrix4 = { { -1.2, 2.3, -3.4, 4.5 }, { 5.6, -6.7, 7.8, -8.9 }, { -9.0, 10.1, -11.2, 12.3 }, { 13.4, -14.5, 15.6, -16.7 } };
+        assertEquals(2549.1228, DeterminantOfMatrix.DET(matrix4, 4));
+
+    }
+}
