3d-graphing freeware that accepts three variables (quadric surfaces)

[Helicobacter]

I'm looking for a 3D-graphing-freeware that's takes x, y, z variables (axis dependence) because I want to see how the different coefficients and constants change the graph.

I've tried two open-source programs thus far and none of the accepts the equation for ellipsoids.

 

[PerennialII]

What have you tried? gnuplot, grace, kst, labplot, R, scilab, octave, maxima, ncarg, veusz, scigraphica, xd3d, root, visit might suit and are freeware.