A strange bug in rf708_bphysics.C

jonas · March 13, 2022, 4:29pm

thanks for reporting this problem!

Indeed, it’s a bug in the RooFormula that behaves wrongly if one of the variable has just an integer as a name, like RooConst(0.0) whose name is simply “0”. That’s why it works when you give your zero constant a different name, like “dm1” which you tried later where you didn’t hit the bug. So as you noticed, the workaround is easy

I have created a PR to fix the bug:

github.com/root-project/root

[RF] Correctly treat variables with integer names in RooFormula

root-project:master ← guitargeek:RooFormula_2

opened 04:25PM - 13 Mar 22 UTC

guitargeek

+25 -3

In case of named arguments, the RooFormula will replace the argument names with…` x[0]` to `x[n]`. There are two things that can go wrong if RooFormula is not implemented right. First, if there is a variable named "x" it should only be substituted if the matching substring is not followed by "[", to not replace existing x[i]. Second, variables with integer names like "0" should only be substituted if the match is not followed by a "]", again to avoid replacing x[i]. This test checks that these cases are handled correctly. The second case was so far not dealt with correctly, but with this commit it is. A corresponding unit test was also implemented. The preprocessor commands in `RooFormula` were also reorganized slightly, such that one can test the `TPRegexp` backend simply by commenting out the `define ROOFORMULA_HAVE_STD_REGEX`. # This Pull request: ## Changes or fixes: ## Checklist: - [ ] tested changes locally - [ ] updated the docs (if necessary) This PR fixes #

It will be fixed in the next patch release.

Thanks again for reporting and have a nice evening!
Jonas