Jacobi Algorithm for solving Laplace's Equation

It is thus fairly straightforward to extend this equation to the three-dimensional case. Whether we solve Eq. (17) or Eq. (18), the solution strategy remains the same. We know the values of \( u \) at \( i=0 \) or \( i=n+1 \) and at \( j=0 \) or \( j=n+1 \) but we cannot start at one of the boundaries and work our way into and across the system since Eq. (17) requires the knowledge of \( u \) at all of the neighbouring points in order to calculate \( u \) at any given point.