Преобразовать в цикл(ы)

//Ручной счёт y
y[0] = b[0] / U[0][0];
y[1] = (b[1] - U[0][1] * y[0]) / U[1][1];
y[2] = (b[2] - U[0][2] * y[0] - U[1][2] * y[1]) / U[2][2];
y[3] = (b[3] - U[0][3] * y[0] - U[1][3] * y[1] - U[2][3] * y[2]) / U[3][3];
y[4] = (b[4] - U[0][4] * y[0] - U[1][4] * y[1] - U[2][4] * y[2] - U[3][4] * y[3]) / U[4][4];
y[5] = (b[5] - U[0][5] * y[0] - U[1][5] * y[1] - U[2][5] * y[2] - U[3][5] * y[3] - U[4][5] * y[4]) / U[5][5];
 
//Ручной счёт xx
xx[5] = y[5];
xx[4] = y[4] - (L[5][4] * xx[5]);
xx[3] = y[3] - (L[4][3] * xx[4] + L[5][3] * xx[5]);
xx[2] = y[2] - (L[3][2] * xx[3] + L[4][2] * xx[4] + L[5][2] * xx[5]);
xx[1] = y[1] - (L[2][1] * xx[2] + L[3][1] * xx[3] + L[4][1] * xx[4] + L[5][1] * xx[5]);
xx[0] = y[0] - (L[1][0] * xx[1] + L[2][0] * xx[2] + L[3][0] * xx[3] + L[4][0] * xx[4] + L[5][0] * xx[5]);

    for (int i = 0; i < 6; ++i)
    {
        double sum = 0;
        for (int j = 0; j < i; ++j)
            sum += U[j][i] * y[j];
        y[i] = (b[i] - sum) / U[i][i];
    }

for (int i = 5; i >= 0; --i)
{
   double sum = 0;
   for (int j = 5; j > i; --j)
      sum += L[j][i] * xx[j];
   xx[i] = (y[i] - sum);
}