six.mat
loadData('pmtkImages', 'isMatFile', false)
I = imread('digit6.png');

setSeed(2);
%rand('seed',30);
cm = ones(64,3);
cm(:,1:2) = repmat(linspace(1,0,size(cm,1))',1,2);
X = repmat(1:size(I,2),size(I,1),1);
Y = repmat([1:size(I,1)]',1,size(I,2));

%{
figure;
imagesc(I);colormap(cm)
set(gca,'XTickLabel','')
set(gca,'YTickLabel','')
axis([0,29,0,29]);
%}
%sigs = [0.1 1 8];
sigs = [5 5 5 5]; % if large (say 100), field flows in same direction
%alphas = [8 4 32];
alphas = [10 10 30 30