[Ktechlab-devel] Slowmatrix! =)

[P Zoltan]

On Wed, 08 Jul 2009 17:09:52 +0200, Alan Grimes <agrimes at speakeasy.net>  
wrote:

>>   As I mentioned before, I'd like to take a different approach: use the
>> Eigen library instead of custom impelementation. That won't have strange
>> bugs. I want to test it and probably use it to validate the current LU
>> implementation, by using a fuzzy tehnique. If Eigen is fast enough, I'd
>> prefer to keep using it in ktechlab.
>
> It seems that Eigen can only deal with floats, not doubles. =( I tried
> to get help with it but couldn't.


  I'm attaching an example, with doubles. You need to have Eigen in the  
include patch, so compile it with a command like:
  g++ -I /path/whre/eigen/is/ lu-000.cpp -o name_of_the_binary

  For the moment it's a very minimal demo, but basically that's all we need.

>
> Checking linear algebra operations is perfectly straightforward.
>
> Function validateLU() checks performLU(), and the mathtest program in
> testing checks fbsub and performLU().
>
> The only active bug that these two functions have revealed is a row
> permutation bug =\.
>

  Yes, but it's easier to debug if you can have the correct values  
directly, not only an indication about 'here something is wrong'.


>>   About configuration options: we could provide multiple Matrix
>> impelmenations this way, by using the preprocessor defines and setting
>> those using configure.
>
> I was thinking more along the lines of switching on and off whole files,
> but yeah, that's the idea.
>

  Actually we could put different implementations in different files.  
Actually it would be quite useful.
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