Conic Rho value in a sketch

[munners]

Does any body know of a way to use an expression to change the rho value of a conic in a sketch?
I have a series of sketches, each consisting of guidelines and a conic, and each of these conics is used to form a surface.
I have another control sketch that creates different rho values at different positions along the surface. I want to be able to alter the surface geometry by changing the control sketch.

Thanks

Munners

 

[PSI-CAD]

Hi,
Have a look to law curve

Regards
Didier Psaltopoulos

http://www.psi-cad.fr