public class MatrixOperation {  public static int[][] add(int[][] matrix_a, int[][] matrix_b) {    int row = matrix_a.length;    int col = matrix_a[0].length;    int[][] result = new int[row][col];    if (row != matrix_b.length || col != matrix_b[0].length) {      System.out.println("Fault");    } else {      for (int i = 0; i < row; i++) {        for (int j = 0; j < col; j++) {          result[i][j] = matrix_a[i][j] + matrix_b[i][j];        }      }    }    return result;  }  public static int[][] sub(int[][] matrix_a, int[][] matrix_b) {    int row = matrix_a.length;    int col = matrix_a[0].length;    int[][] result = new int[row][col];    if (row != matrix_b.length || col != matrix_b[0].length) {      System.out.println("Fault");    } else {      for (int i = 0; i < row; i++) {        for (int j = 0; j < col; j++) {          result[i][j] = matrix_a[i][j] - matrix_b[i][j];        }      }    }    return result;  }  public static int[][] dot(int[][] matrix_a, int[][] matrix_b) {    /*     * matrix_a's dimention m*p matrix_b's dimention p*n. return dimention     * m*n     */    int row = matrix_a.length;    int col = matrix_a[0].length;    int[][] result = new int[row][col];    if (col != matrix_b.length) {      System.out.println("Fault");    } else {      for (int i = 0; i < row; i++) {        for (int j = 0; j < col; j++) {          result[i][j] = 0;          for (int k = 0; k < col; k++) {            result[i][j] += matrix_a[i][k] * matrix_b[k][j];          }        }      }    }    return result;  }  public static int[][] dot(int[][] matrix_a, int b) {    int row = matrix_a.length;    int col = matrix_a[0].length;    int[][] result = new int[row][col];    for (int i = 0; i < row; i++) {      for (int j = 0; j < col; j++) {        result[i][j] = matrix_a[i][j] * b;      }    }    return result;  }  public static int[][] mul(int[][] matrix_a, int[][] matrix_b) {    /*     * matrix_a's dimention m*n matrix_b's dimention m*n. return dimention     * m*n     */    int row = matrix_a.length;    int col = matrix_a[0].length;    int[][] result = new int[row][col];    if (row != matrix_b.length || col != matrix_b[0].length) {      System.out.println("Fault");    } else {      for (int i = 0; i < row; i++) {        for (int j = 0; j < col; j++) {          result[i][j] = matrix_a[i][j] * matrix_b[i][j];        }      }    }    return result;  }  public static int[][] transport(int[][] matrix_a) {    int row = matrix_a.length;    int col = matrix_a[0].length;    int[][] result = new int[row][col];    for (int i = 0; i < row; i++) {      for (int j = 0; j < col; j++) {        result[j][i] = matrix_a[i][j];      }    }    return result;  }  public static void print(int[][] matrix) {    int row = matrix.length;    int col = matrix[0].length;    for (int i = 0; i < row; i++) {      System.out.print("[");      for (int j = 0; j < col; j++) {        System.out.print(matrix[i][j]);        if (j != col - 1) {          System.out.print(", ");        }      }      System.out.print("]/n");    }  }  public static void main(String[] args) {    int[][] a = { { 1, 2 }, { 3, 4 } };    int[][] b = { { 7, 8 }, { 6, 5 } };    int[][] c = add(a, b);    System.out.println("VeVb武林網測試結果如下：");    System.out.println("matrix a = ");    print(a);    System.out.println("matrix b = ");    print(b);    System.out.println("matrix a + b = ");    print(c);    c = sub(a, b);    System.out.println("matrix a - b = ");    print(c);    int[][] d = dot(a, b);    System.out.println("matrix a dot b = ");    print(d);    int[][] e = dot(a, 3);    System.out.println("matrix a * 3 = ");    print(e);    int[][] f = transport(a);    System.out.println("matrix a.T = ");    print(f);    int[][] g = mul(a, b);    System.out.println("matrix a * b = ");    print(g);  }}