[GiNaC-devel] About a (poor) parity in expressions.
sergstesh at yahoo.com
Mon Oct 18 05:50:08 CEST 2010
--- On Sun, 10/17/10, Vladimir V. Kisil <kisilv at maths.leeds.ac.uk> wrote:
> From: Vladimir V. Kisil <kisilv at maths.leeds.ac.uk>
> Subject: Re: [GiNaC-devel] About a (poor) parity in expressions.
> To: "GiNaC development list" <ginac-devel at ginac.de>, "Sergei Steshenko" <sergstesh at yahoo.com>
> Date: Sunday, October 17, 2010, 2:59 PM
> Dear Sergei,
> >>>>> On Sun, 17 Oct 2010 13:40:19 -0700
> (PDT), Sergei Steshenko <sergstesh at yahoo.com>
> SS> To me it looks like two missing
> rewriting rules.
> Yes, it is so. But if they added to
> GiNaC core this can break
> something in a different place, see the example with
> my own suggestion
> to "add a rewriting rule":
> A hundred of rewriting rules in the core GiNaC will
> make it slow and
> can cause other problems. A couple of rewriting
> rules added in the user's
> code to address a specific issue at the right place
> are much more
> manageable. This what I am doing in my own
> programmes right now.
> Best wishes,
> Vladimir V. Kisil email: kisilv at maths.leeds.ac.uk
> www: http://www.maths.leeds.ac.uk/~kisilv/
So what ? I.e. exp(x) * exp(-x) == exp(x - x) == exp(0) == 1.
So, yet another rewriting rule is missing ?
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