Re: [eigen] [RFC] symbolic computations using eigen

[Benoit Jacob <jacob.benoit.1@xxxxxxxxx>]

2009/2/2 Timothy Hunter <tjhunter@xxxxxxxxxxxx>:
> Hello all,
> I wanted to check some equations in mechanics so I wrote these small classes
> for doing symbolic computations in Eigen. Please find the code attached with
> this mail.
> It offers very basic features like additions,subtractions, products of
> multinomials and can be used as scalar types in Eigen matrices. There is no
> evaluation for the multinomials so far, and the output is handwritten inside
> the class.
> The classes have been on my hard drive for a while and I thought you may
> find these features useful enough for a potential inclusion in Eigen.

Thanks, that was at least an interesting read.

As for inclusion in Eigen, I think that the main prerequisite for this
would be for us to have clear use cases in mind and being confident
that we can cover them with good performance.

Your use case (checking equations) is interesting but this is
basically something for which one would normally use a computer
algebra system such as mathematica: this isn't what we want to compete
against!

Just trying to balance usefulness against maintainance cost :)

Cheers,
Benoit

>
> Note these classes rely on hash_maps for fast lookup. A drawback I found
> with hash maps is that the most time is spent in the constructor. Do you
> know any other structure that offers the same benefits (fast
> insertion/lookup) but does not take as much time to create?
>
> Best regards
>
> Tim Hunter
>
>
> --
> Timothy Hunter
> Student (Stanford University)
>
> T. 404 421 3075