[Insight-users] ITK and netlab

[Bill Lorensen]

What compiler are you using and what optimization? A debug build can
be very slow compared to a release build.

On Tue, Mar 31, 2009 at 5:23 PM, Kaveh Kohan <kaveh.kohan at yahoo.com> wrote:
> Hi Luis,
>
> Thank you for the answer.
>
> I am looking for linear algebra functionally because part of my algorithm
> has massive iterative matrix-matrix product and I am looking for an
> efficient way of performing matrix-matrix product.
>
> I did not find VNL sparse matrix strong enough thus I ended up using gmm++.
> I thought (also they mentioned in their website) that gmm++ is an interface
> to blas/lapck/atlas but unfortunately I see a huge gap between effciency of
> matrix-matrix prodcut between MATLAB and gmm (for matrix size I have: 17sec
> vs. 0.5sec). Hence, I am tryig to close the gap by using various libraries
> including vnl (only for dense matrix-matrix operation). I do not expect to
> be as fast as MATLAB but I feel that I am doing something wrong since the
> gap is too big.
>
> Any help or idea is highly appreciated.
>
> Regards,
> Kaveh
>
> ________________________________
> From: Luis Ibanez <luis.ibanez at kitware.com>
> To: Kaveh Kohan <kaveh.kohan at yahoo.com>
> Cc: insight-users at itk.org
> Sent: Tuesday, March 31, 2009 7:42:58 PM
> Subject: Re: [Insight-users] ITK and netlab
>
> Hi Kaveh,
>
>
> Your first two questions will be better addressed if you post them to
> the VXL users list.
>
> (it is a kind way to say that : we don't really know....)    :-)
>
> --
>
> In the context of ITK, we use VXL mainly for providing the following
> functionalities
>
>     A) Linear algebra solutions
>     B) Optimization
>
> most of the methods for (A) and (B) will be provided by vnl throught
> the vnl_matrix
> and vnl_vector classes. You will find the most used method under the
> directory
>
>                                 Insight/Utilities/vxl/core/vnl/algo
>
>
> Some of these algorithms are implemented in VXL by making calls to functions
> provided by blas, while others are provided by lapack.
>
>
> When we make use of vxl, we rarely expose the internal implementations of
> the
> methods. That is, we never call  the blas or lapack routines directly.
> Instead we
> do this through the C++ API defined by VXL.
>
>
> What specific functionalities do you have in mind ?
>
> Are you looking for Linear Algebra ? or for Optimizations  ? or something
> else ?
>
>
>   Please let us know,
>
>
>         Thanks
>
>
> --------------------------------------------------------------------------------------------------------
> On Tue, Mar 31, 2009 at 10:56 AM, Kaveh Kohan <kaveh.kohan at yahoo.com> wrote:
>> Dear All,
>>
>> I have a question about using and linking ITK programs to the netlib
>> libraries already available in the following folder inside of the ITK
>> directory tree:
>>
>> $ITKDIR/Utilities/vxl/v3p/netlib/blas
>> $ITKDIR/Utilities/vxl/v3p/netlib/lapack
>> $ITKDIR/Utilities/vxl/v3p/netlib/linpack
>> $ITKDIR/Utilities/vxl/v3p/netlib/sparse
>> $ITKDIR/Utilities/vxl/v3p/netlib/libf2c
>> ...
>>
>> Here is my question and I would be thankful if you can help:
>>
>> 1) Does VXL by default uses blas for its operations or one needs to
>> activate
>> special flag to activate it? If yes, does anybody know how I can activate
>> using blas, lapck?
>>
>> 2) When one calls VNL class, does it use lapack, blas or one needs to set
>> a
>> flag for it?
>>
>> 3) Is there any example about using blas, lack inside of itk programs?
>>
>> Thanks,
>> Kaveh
>>
>>
>>
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>
>
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