Re: Sparse-merge

[Richard Hindmarsh]

Thanks for your comments David, John

> I have to agree with John on this, you can't use any matlab code 
> whatsoever, at the risk of being accused of copyright violation.... I 
> consider the help available on the mathworks website as open game for 
> developing compatiability code, at least in terms of a specification 
> of the interface, but again don't copy it when you write the help for 
> the functions.
>
> I also consider that cross-comparison of the outputs for octave and 
> matlab implementations is fair game. However, I never look at the 
> matlab dot-m files at the risk of finding myself writing the same code 
> even accidentally. This makes life slightly harder of course...
I understand and agree myself - I was more trying to get a sense of what 
the thinking was in this potentially difficult area - especially as 
Octave has made such fantastic progress recently.

> ARPACK is needed for the eigs function and the svds function, and 
> would then be interfaced to the rank, etc functions to allow them to 
> work. This shouldn't be a major development for a person familar with 
> ARPACK and oct-files. The main issue would be one of packaging, the 
> way John is leaning I think he would expect ARPACK to be an external 
> library with an autoconf function to detect its presence. Then the 
> eigs.cc and svds.cc code would link to this library if present or 
> build a stub version that throws an error.
>
> In any case, we'd welcome any inputs, and I would give pointers once 
> you start..
I think realistically what I can do is write an interface to ARPACK for 
my needs keeping in mind the possibility of an "eigs" implementation and 
see how near that gets us to such an implementation.

As I mentioned previously, the conjugate gradient routines on the sparse 
wishlist are potentially available (presumably freely) on netlib 
("Templates ..." by various people including Dongarra). Being m-files 
they might not be optimally fast, but if its a matter of testing and 
modifying them for Octave I might be able to help there. Or is there a 
reason for avoiding them?

Regards
Richard



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