Re: [eigen] TriangularView::solve() interface

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

2009/8/24 Jitse Niesen <jitse@xxxxxxxxxxxxxxxxx>:
> Hello,
>
> While rewriting part of the tutorial, I noticed that the new
> TriangularView::solve() function returns the solution vector, while the
> other solve functions pass the solution via one of the parameters. Compare
>
>   x = A.triangularView<UpperTriangular>().solve(b);
>
> with
>
>   A.partialLu().solve(b, &x);
>
> Was this done on purpose?

Hm, question for Gael, but indeed this is a bit strange. we need to
unify how we use a single given word thoughout eigen.

>
> The docs on the eigen website [1] were magically updated,

Thanks to Thomas who has set a cron job on his machine!


> but some of the
> latex was not parsed correctly. Am I doing anything wrong? Everything works
> fine on my own computer.

I didn't know about the "aligned" environment, perhaps it requires a
special package. The standard way to do that would be eqnarray*. Then
you put & on both sides of =. This will also look better.

> Something to perhaps add to the to-do list: a routine to estimate the
> condition number of a matrix based on the LU decomposition.

Is that possible at all? I assume that by condition number we mean the
ratio between the biggest and smallest eigenvalue. I don't think that
the LU decomposition sees that! The SVD, Schur, and diagonalizations
are the ones that can be used here.

Benoit