add lattice

common/lattice.m

@@ -0,0 +1,17 @@
+function A = lattice( sz )
+% Create an undirected graph corresponding to sz lattice
+% Example:
+%   plot(graph(lattice([2,2,3])))
+% Input:
+%   sz: 1 x d size of lattice
+% Output:
+%   A: prod(sz) x prod(sz) adjacent matrix of an undirected graph
+% Written by Mo Chen ([email protected])
+d = numel(sz);
+step = cumprod(sz);
+n = step(end);
+M = reshape(1:n,sz);
+S = arrayfun(@(i) reshape(slice(M,i,1:sz(i)-1),1,[]), 1:d,'UniformOutput',false);
+T = arrayfun(@(i) reshape(slice(M,i,2:sz(i)),1,[]), 1:d,'UniformOutput',false);
+A = sparse([S{:}],[T{:}],1,n,n);
+A = A+A';