Re: [ublas] About SuperLU and other stuff

From: Dan Elliott (dan_elliott_at_[hidden])
Date: 2005-05-27 11:20:46

Karl Meerbergen wrote:

>On Thursday 26 May 2005 16:52, Paul C. Leopardi wrote:
>  
>
>>Dear Dan,
>>Yes, you can use uBLAS to invert matrices, but this might not be the
>>optimal way to do it. You use UBLAS to invert a matrix by doing solves on
>>each column of a unit matrix.
>>GluCat uses the uBLAS routines, originally because Joerg Walter wrote them
>>specially for GluCat, and then because it was the easiest thing to do.
>>Best regards
>>    
>>
>
>In general computing the inverse of a matrix is a very bad idea. It is very 
>expensive and numerically less relible than using a backtransformation. 
>
Perhaps my numerical methods knowledge is not where it should be; i 
typically diagonalize the matrix using LU and then solve.  Is 
backtransformation something different/better?  Where would I find a 
library to do this?

>For a 
>sparse matrix, I am sure that SuperLU is a lot more efficient than the ublas 
>lu.
>
>  
>
Are there SuperLU bindings?  What library do you suggest for inverting 
dense matrices?  By the way, what is the status of the bindings?  Where 
should I get the latest version (they are not an official part of 
BOOST/uBLAS)?  Lastly, is it suggested that those of us who are actively 
using uBLAS stay up to date with the unofficial CVS (not the BOOST one)?

>Have a nice day,
>
>  
>
Same to you!  Thanks to all those actively working on uBLAS!  It is great.

- dan

>>On Thu, 26 May 2005 11:53 am, Dan Elliott wrote:
>>    
>>
>>>Paul C. Leopardi wrote:
>>>      
>>>
>>>>Dear Luca,
>>>>Reply below. Best regards
>>>>
>>>>On Sun, 22 May 2005 02:46 am, luca regini wrote:
>>>>        
>>>>
>>>>>I am writing a scientific application. For the moment my vectors are
>>>>>just dinamically allocated array of doubles.
>>>>>To use UBLAS should i rewrite the code to use UBLAS' vector or is there
>>>>>an adapter??
>>>>>After performing some sparse matrix computations i must solve a system
>>>>>using SuperLU. What's the state of
>>>>>the driver?? How does the driver behave? Does it copy stuff and
>>>>>allocate new memory??
>>>>>          
>>>>>
>>>>Have you tried using uBLAS lu_factorize and lu_substitute, defined in
>>>>lu.h ? Do you know how it compares to SuperLU ? Has anyone made this
>>>>comparison ? Also, how large are your sparse matrices?
>>>>        
>>>>
>>>Does this mean we can invert uBLAS matrices using uBLAS routines.  I was
>>>under the impression we had to make use of an external library to solve.
>>>
>>>thanks.
>>>
>>>- dan
>>>_______________________________________________
>>>ublas mailing list
>>>ublas_at_[hidden]
>>>http://lists.boost.org/mailman/listinfo.cgi/ublas
>>>      
>>>
>>_______________________________________________
>>ublas mailing list
>>ublas_at_[hidden]
>>http://lists.boost.org/mailman/listinfo.cgi/ublas
>>    
>>
>
>  
>