[GiNaC-list] Parse error involving factorial symbol
Vladimir V. Kisil
V.Kisil at leeds.ac.uk
Sat May 15 22:01:49 CEST 2021
Dear Roberto,
Yes, normalisation methods in GiNaC undergone some modification
over that period as well. Thus particular form of the expression can
be different now.
Best wishes,
Vladimir
--
Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/
Book: Geometry of Mobius Maps https://doi.org/10.1142/p835
Soft: Geometry of cycles http://moebinv.sourceforge.net/
Jupyter notebooks: https://github.com/vvkisil/MoebInv-notebooks
>>>>> On Fri, 14 May 2021 22:36:13 +0200, Roberto Bagnara <bagnara at cs.unipr.it> said:
RB> On 5/14/21 3:33 PM, Vladimir V. Kisil wrote:
>>>>>>> On Fri, 14 May 2021 15:08:09 +0200, Roberto Bagnara
>>>>>>> <bagnara at cs.unipr.it> said:
RB> On 5/14/21 9:52 AM, Vladimir V. Kisil wrote:
>> >> Dear Roberto! It seems that Ginsh and parser in GiNaC are >>
>> implemented differently. Ginsh understands postfix factorial >>
>> notation like "3!" but GiNaC parser is not. GiNaC parser is >>
>> still happy with "factorial(3)". Best wishes, Vladimir
>> >>
RB> Thanks Vladimir! But please help me understand: I did not
RB> change anything in the part of the code invoking the GiNaC
RB> parser, and I did not change the tests. So the situation you
RB> are describing, i.e., GiNaC parser not understanding postfix
RB> factorial notation, is something that changed from, say, 10
RB> years ago. In other words, do you agree that, say, 10 years
RB> ago, the GiNaC parser was accepting that notation?
>> It seems that before 2008-08-21 GiNaC and Ginsh had used the same
>> parser, which Ginsh is using till now. After a patch they
>> diverged in this respect. So it is quite well possible that your
>> code was running with the old version of GiNaC but cannot do this
>> now without some alteration.
RB> Dear Vladimir,
RB> This explains everything. Now I am investigating failures in
RB> the regression test-suite. One of the most promising examples
RB> for my diagnosis efforts is this:
RB> simplification for output of
RB> -1+1/12*sqrt(sqrt(3)*sqrt(12))*sqrt(12)+1/12*sqrt(-sqrt(3)*sqrt(12))*sqrt(12)
RB> was expected to be -1+(1/2+1/2*I)*sqrt(2) but resulted in
RB> -1+(1/2+1/2*I)*4^(1/4)
RB> From what you write I gather that back in 2008, or even before,
RB> we obtained sqrt(2) where we now obtain 4^(1/4).
RB> Thanks,
RB> Roberto
RB> -- Prof. Roberto Bagnara Applied Formal Methods Laboratory
RB> Department of Mathematical, Physical and Computer Sciences
RB> University of Parma, Italy http://www.cs.unipr.it/~bagnara/
RB> mailto:bagnara at cs.unipr.it
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