[ff3d-users] trivial solution

[Neil Christensen]

Hi,
   I am trying solve the pde:

   div(grad(phi))  + phi = 0

with the boundary condition

   phi = 0 on <1,0,0>.

As you know the analytic solution to this is

   phi = sum_i  a_i cos(k_i . r) + b_i sin(k_i . r)

where a_i, b_i and k_i are chosen such that the boundary condition is 
satisfied.  In my first attempt, the boundary I used was a square.  The 
problem is that when I run ff3d on it, I only get the trivial solution 
phi = 0.  How can I get other solutions?
   Thank you,
Neil