Question

Topic Ch. 10 : Write a class definition for a 2x2 matrix, with methods for get(i,j), set(i,j,v) for getting and setting (i,j)-the entry where i is the row index 0 or 1, and j is the column index 0 or 1, and set() sets the entry in row i and column j to be v, a method for adding a matrix y to given x (e.g. x.add(y) will set x=x+y where the corresponding matrix entries are added), for multiplying( e.g. x.mul(y) will set x=x*y,) and x.det() will return the determinant of x (given that the determinant of x is x[0][0]*x[1][1]-x[1][0]*x[0][1]).  Also add 2 constructors, one that initializes all elements to 0, and another that initializes to a given matrix  double y[2][2] (e.g. mat x(y) will set x=y; Note that x is of class type mat, but y is a 2x2 matrix here.). Also add the methods x.read() and x.print()  for reading (all the 4 elements of the matrix) using cin and for printing (all the 4 elements of the matrix) using cout. Write a main() function that reads two matirces x,y, sets x=x+y, y=y*x, prints x, y, and determinant of x to cout. The data member double mat[2][2] must be a private member.

Answer 1

#include <iostream>

using namespace std;

class matrices

{

public:

void set(int i,int j,double v){

    x[i][j]=v;

}

double get(int i,int j){

        return x[i][j];

}

double add(double y[2][2]){

    for(int i=0;i<2;i++){
        for(int j=0;j<2;j++){
            x[i][j]+=y[i][j];
        }
    }

}

double multiply(double y[2][2]){

    int sum=0;

    for (int c = 0; c < 2; c++) {
      for (int d = 0; d < 2; d++) {
        for (int k = 0; k < 2; k++) {
          sum = sum + x[c][k]*y[k][d];
        }

        mul[c][d] = sum;
        sum = 0;
      }
    }

}

double det(double x[2][2]){

    double deter = x[0][0]*x[1][1]-x[0][1]*x[1][0];
    return deter;

}

matrices(){

    for(int i=0;i<2;i++){
        for(int j=0;j<2;j++){
            x[i][j]=0;
        }
    }

}

matrices(double y[2][2]){

    for(int i=0;i<2;i++){
        for(int j=0;j<2;j++){
            x[i][j]=y[i][j];
        }
    }

}

private:

    double x[2][2];
    double mul[2][2];
};

int main(){

    matrices mat;

    double y[2][2],x[2][2];

    cout<<"enter the matrix x (2x2) : "<<endl;

    for(int i=0;i<2;i++){
        for(int j=0;j<2;j++){
            cin>>x[i][j];
        }
    }

    cout<<"enter the matrix y (2x2) : "<<endl;

    for(int i=0;i<2;i++){
        for(int j=0;j<2;j++){
            cin>>y[i][j];
        }
    }

    mat.add(y);
    mat.multiply(y);

    cout<<"determinant of matrix X is "<<mat.det(x)<<endl;

    return 0;
}