[GiNaC-list] Parse error involving factorial symbol

[Vladimir V. Kisil]

	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