--- On Sun, 10/17/10, Vladimir V. Kisil <kisilv@maths.leeds.ac.uk> wrote:
From: Vladimir V. Kisil <kisilv@maths.leeds.ac.uk> Subject: Re: [GiNaC-devel] About a (poor) parity in expressions. To: "GiNaC development list" <ginac-devel@ginac.de>, "Sergei Steshenko" <sergstesh@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@yahoo.com> said: 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":
http://www.ginac.de/pipermail/ginac-devel/2009-October/001678.html
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 -- Vladimir V. Kisil email: kisilv@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 ? Thanks, Sergei.