How to make a solid of revolution along the y-axis for a function with complex parts?

Hi,

I'm trying to make a solid of revolution given the following function:

The graph would look like the upper part of an oval with major axis lenght of 9.

What I'm trying to do is to generate a solid of revolution that revolves around the y-axis rather than the x-axis.

I've tested the following code to no avail:

X = 0:0.1:pi;
R = real((9 - (1/2).*((X - 7).^(1/2))).^(1/2));
[z,x,y] = cylinder(R);
surf(x,y,z)

As it can be seen, it generates (evidently) a cylinder, so I'm guessing my approach isn't the right one for this problem.

My final goal is to generate the upper and lower surface of torus-like object. Any idea on how to do this?

Thanks :)

Answer 1

[Matt J]

X = 0:0.1:pi;
R = sqrt(9-0.5*(X-7).^2); R(imag(R)~=0)=nan;
[z,x,y] = cylinder(R);
surf(x,y,z); xlabel X;ylabel Y; zlabel Z; axis equal

[Marco Cordero]

Oh well, that was quick.

Thank you Matt!