Morph a graph into another graph?

Hi, I got a question asking me to smoothly morph the graph of y = x^2 + y^2 into a graph of y = -x^2 + y^2 and back again. I used the function morph but it does not work. I wonder is there any other functions/syntax to this? Any information is helpful. Thanks.

Answer 1

[Star Strider]

One approach:

[X,Y] = meshgrid(linspace(-5, 5, 50));
fcn = @(x,y,k) k*x.^2 + y.^2;

v = [1:-0.05:-1;  -1:0.05:1];
for k1 = 1:2
    for k2 = v(k1,:)
        surf(X, Y, fcn(X,Y,k2))
        axis([-5  5    -5  5    -40  60])
        drawnow
        pause(0.1)
    end
end