Dear all,

I have a question concerning the usage of RecursiveFraction for RooAddPdf.

I have a signal PDF which is made by 3 PDFs and each of the 3 sub-PDF by a sum of 3 PDfFs.

I.e

SignalModel = frac1 * PDF1 + frac2 * PDF2 + [%] * PDF3.

The frac1, frac2 are fix and constant values however inside PDF2 expands to

PDF2 = frac2_1 * PDF2_1 + frac2_2 * PDF2_2 + [%] * PDF3.

What i want to do in my fitter is to have

```
frac2_2 ---> scale * frac_2_2(original)
```

I.e scale the fraction of one sub-pdf component by a factor and let still the internal PDF2_1 to be normalized to 1.

When i construct my fractions i compute the recursive “numbers” by myself but when i want to “scale” them i am not anymore sure if the scale parameter has to be propagated on the redefinition of the “other” non-scaled fractions or not.

I hope i have been clear on what i am trying to achieve.

Thanks in advance

Renato

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