[PURRS-devel] [Fwd: Re: Strange behavior of numer_denom]

Roberto Bagnara bagnara at cs.unipr.it
Mon Jun 30 21:46:22 CEST 2003



-------- Original Message --------
Subject: Re: Strange behavior of numer_denom
Date: Mon, 30 Jun 2003 20:07:58 +0200
From: Christian Bauer <Christian.Bauer at Uni-Mainz.DE>
Reply-To: ginac-list at zino.physik.uni-mainz.de
To: ginac-list at zino.physik.uni-mainz.de
References: <3EFFEFC8.2090203 at cs.unipr.it>

Hi!

On Mon, Jun 30, 2003 at 10:07:36AM +0200, Roberto Bagnara wrote:
> There are two problems here: (1) the numerator and denominator returned
> are trivially not coprime;

numer_denom() and normal() have a problem with square roots that get
squared in the process, which I suspect is what happens here (1264 = 16*79).
Patches are welcome...

> and (2) numer_denom does not behave like a mathematical function. With the
> same input, it produces the sequence of answers
> 
> {-1264*d,-1264}
> {1264*d,1264}
> [...]

The denominator should always be unit normal (= positive in this case).
This problem should now be fixed in CVS.

Bye,
Christian

-- 
   / Physics is an algorithm
\/ http://www.uni-mainz.de/~bauec002/


-- 
Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara at cs.unipr.it




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