Re: [ublas] Does uBLAS work with dd_real and qd_real ?

Subject: Re: [ublas] Does uBLAS work with dd_real and qd_real ?
From: Nasos Iliopoulos (nasos_i_at_[hidden])
Date: 2010-03-24 07:27:15

Hi Paul,
I have used ublas in the past with GNU multi precision library through the C++ class based interface and did not have any troubles, although I did not test it extensively. The only downside is the dramatic speed decrease that after all you cannot avoid with multi-prec. arithmetic. 

On the other hand I don't find why uBlas should have trouble, since it just requires appropriate numeric semantics. If a type library is not implementing those properly you may be getting problems like you mention (although I believe it is difficult to be the case).  

Here is a long shot: there is the possibility that qq_real classes
require some aligned memory access that afaik is not supported by ublas
containers, but I think this may be something worth considering in the
future having in mind the hype with GPUs and vectorization of
algorithms.

I am not aware of any ready-implemented tests that would allow you to infiltrate through the problem you describe. I guess some exhaustive debuging on small matrices (like 2x2 or 3x3) could be the only way. If you could post an example I might be able to test it.

Best 
Nasos

> From: paul.leopardi_at_[hidden]
> To: ublas_at_[hidden]
> Date: Wed, 24 Mar 2010 12:38:09 +1100
> Subject: [ublas] Does uBLAS work with dd_real and qd_real ?
> 
> Hi all,
> Has anyone here worked with dd_real or qd_real (from qd-2.3.7 
> http://www.cs.berkeley.edu/~yozo/ ) and uBLAS? My testing of these classes in 
> the context of GluCat has resulted in peculiar errors in matrix results that 
> look like they occur somewhere within uBLAS matrix multiplication (or possibly 
> other operations) for matrix< dd_real, row_major > dense matrices.
> 
> Is there a test suite I could use to narrow down the cause of the errors, or 
> are there any known errors in the use of uBLAS with high and arbitrary 
> precision floating point?
> Thanks, Paul
> _______________________________________________
> ublas mailing list
> ublas_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/ublas
> Sent to: nasos_i_at_[hidden]
                                               
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