% SQGRIDORDER  Demo of nested disection order for square grids
% (Ed Bueler 2/27/02)

N=30;  % Try N small (e.g. N=6) and actually look at grid g
       %   to see the ordering produced by nested dissection 'N'
       %   vs. standard ordering 'S' on the square.

clf;
g=numgrid('S',N); A=delsq(g);
subplot(2,2,1), spy(A); title('Standard order: A');
[l,u]=lu(A); subplot(2,2,2), spy(u); title('and U');

g=numgrid('N',N); A=delsq(g);
subplot(2,2,3), spy(A); title('Nested dissect: A');
[l,u]=lu(A); subplot(2,2,4), spy(u);  title('and U');