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Ublas : |
Subject: Re: [ublas] Getting bit by ormqr.hpp
From: Karl Meerbergen (Karl.Meerbergen_at_[hidden])
Date: 2008-10-16 09:21:40
You are right of course. This should be corrected.
Thanks for spotting this
Karl
Jeremy Conlin wrote:
> I have been using ormqr.hpp and recently got an error message saying:
>
> Parameter 2 to routine ZUNMQR was incorrect
>
> This parameter indicates whether a conjugate transpose is to be taken
> when applying a matrix Q. The valid options for the complex version
> are 'N' or 'C' (standing for No transpose or Conjugate transpose
> respectively) while for the single or double version, [DS]ORMQR the
> valid options are 'N' or 'T' (for No transpose or Transpose
> respectively). Now the reason I had a problem was because I passed
> 'T' to the complex version.
>
> In ormqr.hpp there is an assert statment to ensure only valid options
> are passed to ormqr generally:
>
> assert ( trans=='N' || trans=='C' || trans=='T' );
>
> This obviously didn't catch my problem. It is easy to move this
> assertion into the more specific functions of ormqr that just call the
> LAPACK versions. This way you would have one of the two statements
> below and could avoid the error I got this morning.
>
> assert ( trans=='N' || trans=='T'); // For single or double
> precision
> assert ( trans=='N' || trans=='C'); // For complex numbers
>
> I can make this change and submit a patch, but I wanted to get others'
> opinions. It seems like the specific functions "want" to remain clean
> and only make the call to LAPACK and nothing else. That is why I
> hesitate to put the assert in them.
>
> What do you think is the best thing to do? I hope my explanation was
> clear enough.
>
> Thanks,
> Jeremy Conlin
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