Difference in integral function in Root version 6.24 and 6.22

ROOT
1

I am trying to perform an integration in root using [x= a->Integral(0.15,20.0);]. What I observe is that the same code in root 6.24 and 6.22 is giving different results. Although the difference is not much, but still significant. Could anyone please tell me is the method of integration performed by integral function in both the version of root are different?

Thanks in advance
Suman

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Hi @Suman_Deb ,
and welcome to the ROOT forum! Sorry for the late reply, we need @jonas or @moneta to help, let’s ping them.

Cheers,
Enrico

3

Hi,
It could be the method is different depending if you are using the libMathMore.so based on GSL. If it is available it is used, since the integration method is superior. So it could be that in one of the version you are using MathMore and the other not.
You can change the integration method by calling ROOT::Math::IntegratorOneDimOptions::SetDefaultIntegrator(name).
The name can be AdaptiveSingular available in MathMode or for example Gauss, available in MathCore.
If you still have a difference when using the same algorithm (e.g. Gauss), please let us know and post the code reproducing the problem.

Best Regards

Lorenzo

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