Java Program to Find the Determinant of a Matrix

// Java program to find // Determinant of a matrix // using recursion class Geeks {  // Dimension of input square matrix  static final int N = 2;  // Function to get cofactor of  // mat[p][q] in temp[][]. n is  // current dimension of mat[][]  static void getCofactor(int mat[][], int temp[][],  int p, int q, int n)  {  int i = 0, j = 0;  // Looping for each element  // of the matrix  for (int row = 0; row < n; row++) {  for (int col = 0; col < n; col++) {    // Copying into temporary matrix  // only those element which are  // not in given row and column  if (row != p && col != q) {  temp[i][j++] = mat[row][col];    // Row is filled, so increase  // row index and reset col index  if (j == n - 1) {  j = 0;  i++;  }  }  }  }  }  /* Recursive function for finding determinant  of matrix. n is current dimension of mat[][]. */  static int determinantOfMatrix(int mat[][], int n)  {  int D = 0; // Initialize result  // Base case : if matrix  // contains single element  if (n == 1)  return mat[0][0];  // To store cofactors  int temp[][] = new int[N][N];  // To store sign multiplier  int sign = 1;  // Iterate for each element of first row  for (int f = 0; f < n; f++) {    // Getting Cofactor of mat[0][f]  getCofactor(mat, temp, 0, f, n);  D += sign * mat[0][f]  * determinantOfMatrix(temp, n - 1);  // terms are to be added  // with alternate sign  sign = -sign;  }  return D;  }  // function for displaying the matrix   static void display(int mat[][], int row, int col)  {  for (int i = 0; i < row; i++) {  for (int j = 0; j < col; j++)  System.out.print(mat[i][j]);  System.out.print("\n");  }  }  // Driver code  public static void main(String[] args)  {  int mat[][] = { { 4, 3 }, { 2, 3 } };  System.out.print("Determinant "  + "of the matrix is: "  + determinantOfMatrix(mat, N));  } } 

// Java program to find Determinant of a matrix class Geeks {  // Dimension of input square matrix  static final int N = 4;  // Function to get determinant of matrix  static int determinantOfMatrix(int mat[][], int n)  {  int num1, num2, det = 1, index,  total = 1; // Initialize result  // temporary array for storing row  int[] temp = new int[n + 1];  // loop for traversing the diagonal elements  for (int i = 0; i < n; i++) {  index = i; // initialize the index  // finding the index which has non zero value  while (mat[index][i] == 0 && index < n) {  index++;  }  if (index == n) // if there is non zero element  {  // the determinant of matrix as zero  continue;  }  if (index != i) {    // loop for swapping the diagonal element row  // and index row  for (int j = 0; j < n; j++) {  swap(mat, index, j, i, j);  }  // determinant sign changes when we shift  // rows go through determinant properties  det = (int)(det * Math.pow(-1, index - i));  }  // storing the values of diagonal row elements  for (int j = 0; j < n; j++) {  temp[j] = mat[i][j];  }  // traversing every row below the diagonal  // element  for (int j = i + 1; j < n; j++) {  num1 = temp[i]; // value of diagonal element  num2 = mat[j]  [i]; // value of next row element  // traversing every column of row  // and multiplying to every row  for (int k = 0; k < n; k++) {    // multiplying to make the diagonal  // element and next row element equal  mat[j][k] = (num1 * mat[j][k])  - (num2 * temp[k]);  }  total = total * num1; // Det(kA)=kDet(A);  }  }  // multiplying the diagonal elements to get  // determinant  for (int i = 0; i < n; i++) {  det = det * mat[i][i];  }  return (det / total); // Det(kA)/k=Det(A);  }  static int[][] swap(int[][] arr, int i1, int j1, int i2,  int j2)  {  int temp = arr[i1][j1];  arr[i1][j1] = arr[i2][j2];  arr[i2][j2] = temp;  return arr;  }  // Driver code  public static void main(String[] args)  {  int mat[][] = { { 1, 0, 2, -1 },  { 3, 0, 0, 5 },  { 2, 1, 4, -3 },  { 1, 0, 5, 0 } };  // Function call  System.out.printf(  "Determinant of the matrix is: %d",  determinantOfMatrix(mat, N));  } }