Ae = [ 2 1; 1 2]; // ellipse
Ah = [ 1 4; 4 3]; // hyperbola
Ap = [ 1 1; 1 1]; // parabola
Lspace=-2:0.2:2; // Linear spacing
n =size(Lspace,2);
Ze = zeros(n,n);
Zh = zeros(n,n);
Zp = zeros(n,n);
for i = 1:n,
	for j = 1:n
		X = [Lspace(i), Lspace(j)];
		Ze(i,j) = X*Ae*X';
		Zh(i,j) = X*Ah*X';
		Zp(i,j) = X*Ap*X';
	end;
end;
scf(2);
clf();
a=get("current_axes"); a.isoview="on"; // aspect ratio 1:1
square(-2,-2,2,2); // window ratio 1:1
id = color("darkgreen"); // define dark green
contour2d(Lspace,Lspace,Ze,[-1,1],style=[2,2]);
contour2d(Lspace,Lspace,Zh,[-1,1],style=[5,5]);
contour2d(Lspace,Lspace,Zp,[-1,1],style=[id,id]);
//xtitle('Scilab Conic Contour Plots','x','y');
legend('Parallel Lines','Ellipse','Hyperbola');
xs2eps(2,'contour.eps');