Re: Symbolic Toolbox

[Peter Gawthrop]

Hi Ben,

        I've been looking around for a good symbolic package for a while
and, like you, had come to the conclusion that GiNac with an Octave
interface would be a very good solution - so I'm very pleased that you
have done it!

        I would be very interested to get a copy of what you have done so
far, use it and feedback experiences to you. I would like to be able to
help development, but unfortunately my C++ experience is minimal.

        Best wishes,

        Peter.

 On Thu, 22 Jun 2000, Ben Sapp wrote:

> A Scottedward Hodel wrote:
> > 
> > Hi Ben,
> > 
> > I just read over your note in more detail.  There have been several requests
> > for symbolic manipulation capabilities in Octave for some time.    I like
> > your demo very much.  That it can be installed in a .oct file makes it
> > that much better as an add-on package.
> 
> Thank you.  
> 
> > How would you propose making the package available?
> 
> Well, I would like to do it the "best" way, whatever that may be. :) 
> Here is what I am currently thinking is best.  However, I am open to
> suggestions.  I think that if I implement it correctly as .oct files
> then it should not be very hard to add it into Octave as regular data
> types and interenal functions.   I would like to do this because if we
> do not I do not see how I could acomplish the following example with
> trigonometric functions: (this example is made up and currently you can
> not do this with my package.)
> 
> ******************************************
> octave:5> x = sym("x");
> octave:6> a = x+sin(x^2);
> octave:7> differentiate(a,x)
> ans = 
> 
> 1+2*x*cos(x^2)
> octave:8>  
> ******************************************
> 
> But,  I do not see how I could do this with out modifying the current
> Octave implementation of the internal sin function ... does any one
> else?   Maybe I could change the name slightly like Sin and Cos instead
> of sin and cos?  Is this a good idea?   
> 
> I am also a bit unsure of how to implement matrices of symbolic
> variables.  I could use the matrix class provided in the GiNaC library,
> but I am a bit concerened that then we would have two types of matrix
> implementations in Octave.  This seems sub optimal.  Is it possible to
> use the templates in Octave on your own data types?   I suspect that the
> answer is yes, but it is not clear to me how to do this.   
> 
> Thanks.  
> 
> -- 
> Ben Sapp                         Los Alamos National Laboratory
> email: <mailto:address@hidden>   Phone: (505)667-3277
> Fax:   (505)665-7920             URL:   http://www.neutrino.lanl.gov/
> --
> 
> 
> 
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=============================================================
Professor Peter J. Gawthrop, 
MA, DPhil, FIMechE, FIEE, Sen. Memb. IEEE, C.Eng, Eur. Ing.

Centre for Systems & Control
          and
Department of Mechanical Engineering

Room number: James Watt 603 
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