axis equal
axis off
set(gca, 'Units', 'normalized')
set(gca, 'Position', [0.01 0.01 0.98 0.98])
set(gcf, 'Units', 'inches')
set(gcf, 'Position', [1 1 4 4])
set(gcf, 'PaperUnits', 'inches')
set(gcf, 'PaperPosition', [0 0 4 4], 'PaperSize', [4 4])
figure(gcf)
print -dpdf grid.pdf
disp('Grid printed to file grid.pdf')