CVSROOT: /cvs/purrs
Module name: purrs
Changes by: zolo(a)cs.unipr.it 2003-12-31 17:32:24
Modified files:
src : Recurrence.cc Recurrence.defs.hh
Log message:
Improved the traditional step 3 with the same idea used
in the new method: no longer consider all the homogeneous
part of the solution, but the step 3 is applied k times
(k is the order of the recurrence) on the coefficients of
the symbolic initial conditions occurring in the homogeneous
part of the recurrence.
Other minor improvements.
Patches:
http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/purrs/src/Recurrence.cc.diff?cvsr…http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/purrs/src/Recurrence.defs.hh.diff…
-------- Original Message --------
Subject: Re: [PURRS-devel] base case assumptions
Date: Mon, 29 Dec 2003 21:22:03 -0500
From: Shailesh Humbad <humbads(a)alum.mit.edu>
To: Roberto Bagnara <bagnara(a)cs.unipr.it>
References: <6.0.0.22.0.20031226022754.01ccf318(a)nyip.net>
<3FEF09D2.2040706(a)cs.unipr.it>
Thanks for confirming my suspicion and for making the research demo
available online. It's a very useful tool for those of us who don't
have access to Mathematica.
By the way, when the base cases are defined and a correction term added
to the formula given by PURRS, the solution to the recurrence reduces to
[(n-2)*(n-1)]/2.
Regards,
Shailesh
At 11:50 AM 12/28/2003, you wrote:
>Shailesh Humbad wrote:
>>I am having a problem with the online version of PURRS.
>> I tried it on a recurrence relation derived from an algorithm
>> I'm working on, and the resulting formula is off by one for even n.
>> I believe it may be something to do with our assumptions for the base
>> cases and starting index. Is that something that would affect the results?
>
>Dear Shailesh,
>
>you are right: the online demo assumes that, for a recurrence of order
>k, the initial conditions are given for x(0), ..., x(k-1).
>We are working at a revision of our system (that currently is, remember,
>only a research prototype) that will allow to specify any set of
>initial conditions and special cases.
>We will also extend the online demo so as to make this facilities
>available through the web.
>
>>Thanks and Happy Holidays,
>
>Thanks for your input.
>Have a great 2004,
>
> Roberto Bagnara on behalf of the PURRS team
>
>--
>Prof. Roberto Bagnara
>Computer Science Group
>Department of Mathematics, University of Parma, Italy
>http://www.cs.unipr.it/~bagnara/
>mailto:bagnara@cs.unipr.it
--
Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara@cs.unipr.it
