It depends what CATIA product - Image and Shape, Freestyle Shaper or ICEM? In ICEM it is the Approximation Tab. Deepak is correct in that the Fit spline does roughly the same thing but also "Simplify Spline" will also do this by eliminating knots from the spline - thereby smoothing it. Sounds like you are trying to use a series of connected curves and/or sketches to extrude. Perhaps showing a screen shot would clarify things. Extrude won't extrude if the profile is not closed - is this the case? Perhaps composite curve segments are not connected?
Yes...The Fit Spline command is what i want...
Thanx to both of you...Both of you have the correct answer...i thought i can give points to both answers but i cant..
sorry...i am new here...thanx again for the help...