% Set any negative elements of matrix A to 0.<BR>
% If A is a height field, this "fills" valleys with water<BR>
function A = FillWithWater(A);
<P>
[m,n] = size(A);<BR>
for i = 1:m<BR>
	for j = 1:n<BR>
		if A(i,j) < 0<BR>
			A(i,j) = 0;<BR>
		end<BR>
	end<BR>
end