[GiNaC-devel] About a (poor) parity in expressions.

[Sergei Steshenko]

--- 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>, "Francois Maltey" <fmaltey at nerim.fr>
> Cc: "Vladimir V. Kisil" <kisilv at maths.leeds.ac.uk>
> Date: Sunday, October 17, 2010, 10:28 AM
>        
> Dear Francois,
> 
> >>>>> On Sun, 17 Oct 2010 16:31:20 +0200,
> Francois Maltey <fmaltey at nerim.fr>
> said:
>     FM> After some computations, I offen get a
> result as sin(x)+sin(-x)
>     FM> or cos(x)-cos(-x).
> 
>     I am facing similar situations very
> often. If there is a predictable
>   pattern in the answer I am employing a custom
> replacement (subs()
>   method) with wildcards. This is rather effective and
> much safer than to put
>   it into the core GiNaC.
> 
>   So far software is not smart enough to make all
> possible tricks, it
>   may be reasonable to leave the final touch to
> humans.
> 
>   Best wishes,
>   Vladimir
> -- 
> Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
> --               
>       www: http://www.maths.leeds.ac.uk/~kisilv/
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To me it looks like two missing rewriting rules.

Regards,
  Sergei.