Spline Interpolations

Roofit and RooStats
#1

Hi there,
I have a graph ‘gg3’ defined as TGraphErrors type. I want to get spline interpolations between all the points and also get errors for them. May I know how I do that?
For example, I did the following to get the interpolations:

TSpline3 *s3 = new TSpline3(“grSpl3”,gg3);
interpolX = s3->Eval(x);

That way I could get the value of the interpolation, but not the error on it. Would you please help me if there is a way?

If it’s not too much, may I know what’s the difference between TSpline, TSplinePoly, TSpline3 and TSplinePoly3 and so on?
Thank you.
KP

#2

Hi,
spline is an interpolation process and the points errors (of the TGraphErrors) are not taken into account, so for this reason there is no function returning an Error on the interpolated point.

TSpline3 is a cubic spline, while TSpline5 is a quintic spline. The TSpline is a base class for the two implementations. TSplinePoly are internal classes for representing the internal interpolating function.

Best Regards

Lorenzo

#3

Thanks a lot Lorenzo for your kind answers. I really appreciate it.