[GiNaC-list] Non commutative symbols ?

Vladimir V. Kisil kisilv at maths.leeds.ac.uk
Mon Jun 29 23:01:48 CEST 2009


>>>>> On Mon, 29 Jun 2009 09:41:14 -0700 (PDT), ahabrard <amaury.habrard at lif.univ-mrs.fr> said:
    A> const unsigned tinfo=2; symbol x("x",
    A> return_types::noncommutative,&tinfo)

	Which version of GiNaC you are using, 1.4 branch I suppose? This
  code is not working with the current 1.5 branch. Moreover I could not
  figure out how to make non-commutative symbols at the moment, probably
  a patch is required for this.

  What other developers think, shall we simply add a new class ncsymbol
  derived from symbol?

    A> Ginac stops with the following message: "Terminate called after
    A> throwing an instance of 'std::logic_error'
    A>   what(): add::eval(): sum of non-commutative objects has
    A>   non-zero numeric
    A> term Abort trap"

	GiNaC seems to forbid to make matrices out of non-commutative object
  in order to avoid complications with nested non-commutativities. If
  you know that you want you may need to derive a new class from
  matrices to handle it.

  Best wishes, 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/

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