void Matrix::transpose() {
    if (!arr) return;
    else {
        Matrix temp = *this;    //save current matrix to the temp

        int t = n;
        n = m;
        m = t;                      //swap width and height

        arr = new double*[n];
        for (int i = 0; i < n; i++)
            arr[i] = new double[m];     //allocate memory for transposed matrix

        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                arr[i][j] = temp.arr[j][i];     //fill new matrix with elements from temp
    }
}