Hi Rene!
On Oct 12, 2004, at 10:33 AM, Rene Brun wrote:
> Hi Roland,
>
> It is not clear to me what you want to achieve.
> It looks like what you are requesting is already implemented
> in TTreeFormula.
>
Thanks for the pointer, I had overlooked the comment hinting at
DefinedVariable(). From the verbosity of the documentation I assume
that TTreeFormula is mainly used internally ;-)
> Rene brun
>
> Roland Kuhn wrote:
>>
>> Hi!
>>
>> I'd like to use TFormula's parsing capabilities in a ROOT application.
>> The problem is, that parameters with real names (like "sigma") cannot
>> be readily used since they trigger an error 30 (bad numerical
>> expression). Going through the formula in a pre-parsing step and
>> replacing the names with [0], [1], and so on kind of defeats the
>> purpose of this excercise, as I would need to write a parser myself,
>> which would have to know about all the special names ("sin", ...).
>> Unless someone can suggest a better solution, I would insert some code
>> into TFormula::Analyze so that the "error 30" case (after everything
>> else has been tried) is replaced by looking through the list of
>> parameter names, replacing this token with the appropriate [n] action,
>> adding it to the list first if it didn't yet exist. This should
>> probably be configurable as it changes the user interface
>> considerably.
>> It's the first time I dig so deeply into ROOT, so if you have any help
>> to offer, I would kindly accept any suggestions you wanted to make.
>>
>> Ciao,
>> Roland
>>
>> --
>> TU Muenchen, Physik-Department E18, James-Franck-Str. 85747 Garching
>> Telefon 089/289-12592; Telefax 089/289-12570
>> --
>> A mouse is a device used to point at
>> the xterm you want to type in.
>> Kim Alm on a.s.r.
>>
>>
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Ciao,
Roland
--
TU Muenchen, Physik-Department E18, James-Franck-Str. 85747 Garching
Telefon 089/289-12592; Telefax 089/289-12570
--
A mouse is a device used to point at
the xterm you want to type in.
Kim Alm on a.s.r.
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