How do I plot a 3d graph for a transfer function in MATLAB?

[rlspin]

Matlab 3d graph help

I'm pretty new to MATLAB so I am sorry if this is a stupid question but how do i produce a 3d graph for a transfer function?
Just for arguments sake, a simple TF like this:
2
-------------
s^2 + 2 s + 3

 

[MATLABdude]

Well, what are you trying to plot? Bode plots are sometimes plotted, but 3D? I suppose you could plot some kind of contour plot against complex values of s...

 

[rlspin]

Sorry, that was a bad example. Say I had this transfer function instead:
2
-------------
s^2 + 2Xs + 3

and I had various values for X. I understand how i would plot the various curves on one graph in 2D but is there a way to 3d graph for the same results?

 

[MATLABdude]

Okay, so assuming you're plotting magnitude as a function of various frequencies and values of X, you'd have to plot a surface or mesh plot. (You'll also probably need the meshgrid option).

meshgrid:
http://www.mathworks.com/access/helpdesk/help/techdoc/ref/meshgrid.html

surface plot:
http://www.mathworks.com/access/helpdesk/help/techdoc/ref/surf.html

mesh plot:
http://www.mathworks.com/access/helpdesk/help/techdoc/ref/mesh.html