# public class Matrix2x2 private double matrix new double public double

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92``` ```public class Matrix2x2 { private double[][]matrix = new double[2][2]; public double[][] getMatrix() { return matrix; } public void setMatrix(double[][] matrix) { this.matrix = matrix; } public Matrix2x2() { this(new double[][]{{0,0},{0,0}}); } public Matrix2x2(double c) { this(new double[][]{{c,c},{c,c}}); } public Matrix2x2(double[][] matrix) { this.matrix = matrix; } public Matrix2x2(double b1, double b2, double b3, double b4) { this(new double[][]{{b1,b2},{b3,b4}}); } public Matrix2x2 add(Matrix2x2 matr) { Matrix2x2 result = new Matrix2x2(); for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { result.matrix[i][j] = this.matrix[i][j] + matr.matrix[i][j]; } } return result; } public void add2(Matrix2x2 matr) { for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { this.matrix[i][j] += matr.matrix[i][j]; } } } public Matrix2x2 sub(Matrix2x2 matr) { Matrix2x2 result = new Matrix2x2(); for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { result.matrix[i][j] = this.matrix[i][j] - matr.matrix[i][j]; } } return result; } public void sub2(Matrix2x2 matr) { for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { this.matrix[i][j] -= matr.matrix[i][j]; } } } public Matrix2x2 multNumber(double v) { Matrix2x2 result = new Matrix2x2(); for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { result.matrix[i][j] = this.matrix[i][j] * v; } } return result; } public void multNumber2(double v) { for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { this.matrix[i][j] *= v; } } } public Matrix2x2 mult(Matrix2x2 matr) { Matrix2x2 result = new Matrix2x2(); for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { for (int k = 0; k < 2; k++) { result.matrix[i][j] += this.matrix[i][k] * matr.matrix[k][j]; } } } return result; } public void mult2(Matrix2x2 matr) { for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { for (int k = 0; k < 2; k++) { this.matrix[i][j] += this.matrix[i][k] * matr.matrix[k][j]; } } } } } ```