quicwind/poisson_fft3q.m

   1 function u=poisson_fft3q(f,h)
   2 % solve poisson equation with QUIC boundary conditions:
   3 % lambda = 0 top and size, dlambda/dz = 0 on the bottom
   4 n=size(f);
   5 % reflect top to the bottom
   6 r = zeros(n(1),n(2),2*n(3));
   7 r(:,:,1:n(3))=f(:,:,n(3):-1:1);
   8 r(:,:,n(3)+1:2*n(3))=f;
   9 % solve with zero boundary conditions
  10 u=poisson_fft3z(r,h);
  11 % check up and down symmetry
  12 err_sym = big(u(:,:,n(3):-1:1)-u(:,:,n(3)+1:2*n(3)))
  13 % return upper half
  14 u = u(:,:,n(3)+1:2*n(3));