Subject: Re: [ublas] unsubscribe??
From: sguazt (marco.guazzone_at_[hidden])
Date: 2012-10-10 02:06:57
On Tue, Oct 9, 2012 at 3:31 PM, Dhruv Bhatt <bhattdh_at_[hidden]> wrote:
> How do I unsubscribe from this mailing list?
Never tried, but if you follow this link
at the end of the page there is a section for "ublas Subscribers"
where you can actually unsubscribe from the list:
"... To unsubscribe from ublas, get a password reminder, or change
your subscription options enter your subscription email address:.."
> Thank you,
> Dhruv Bhatt
> Software Developer
> Phone: (704) 501-1713
> From: Rutger ter Borg <rutger_at_[hidden]>
> To: ublas_at_[hidden]
> Date: 10/09/2012 03:55 AM
> Subject: Re: [ublas] [BLAS bindings] help appreciated on using trmv
> and gbmv
> Sent by: ublas-bounces_at_[hidden]
> On 2012-10-08 14:33, Florent Teichteil wrote:
>> You're right, computations with trmv are correct with values of
>> reasonable magnitudes, let say between -500 and 500 for instance.
>> Actually, I figured out why it didn't work with very large values up to
>> RAND_MAX: depending on the computations performed by gemv or trmv, some
>> temporary values exceeded the maximum value that can be represented by a
>> double number (for instance, RAND_MAX * RAND_MAX can not be represented
>> using double precision numbers).
>> That said... The bindings for banded matrices, i.e. gbmv, still give
>> incorrect results with matrices and vectors filled with reasonable
>> values. Moreover, the only transpose operator that makes sense
>> (according to your previous post), does not compile with
>> banded_adaptors. So:
>> 1. How can I get correct results with gbmv (even with matrices and
>> vectors filled with the same value of 1.0)?
>> 2. How can I transpose a banded-adapted matrix before calling gbmv,
>> using boost::numeric::bindings::trans?
> Hello Florent,
> 1) you don't clear the banded matrix B, in my case M != B. If you do
> that, the routines using the packed banded storage start to work.
> blas::gbmv assumes packed storage.
> 2) The banded adaptor of the dense matrix doesn't work with blas::gbmv
> because the memory model isn't compatible. Maybe we can apply a trick to
> the memory model, such as passing a* = begin_value(A)-kl and lda += 1?
> We would need to check that. Until then, it is not supported.
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