function [Z]=makedomain(n);
// prepares a DEM of a special kind
for i=1:1:n
for j=1:1:n
x=i/n; y=j/n;
diff=1-(x+0.2)^2-(y+0.1)^2; // inside or outside?
if diff<0
slop=1/2; // different slopes inside
else
slop=2; //and outside
end;
Z(i,j)=slop*abs(diff)+1/(99+abs(diff))*rand(1,1)+0.9*y;
// decrease 99 to increase the randomization
end;
end;
endfunction;