<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:14pt"><div>Hi Luis,<br><br>Thank you for the answer.<br><br>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.<br><br>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.<br><br>Any help or idea is highly appreciated.<br><br>Regards,<br>Kaveh<br></div><div style="font-family: times new roman,new york,times,serif; font-size: 14pt;"><br><div style="font-family: arial,helvetica,sans-serif; font-size: 13px;"><font size="2" face="Tahoma"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Luis Ibanez <luis.ibanez@kitware.com><br><b><span style="font-weight: bold;">To:</span></b> Kaveh Kohan <kaveh.kohan@yahoo.com><br><b><span style="font-weight: bold;">Cc:</span></b> insight-users@itk.org<br><b><span style="font-weight: bold;">Sent:</span></b> Tuesday, March 31, 2009 7:42:58 PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [Insight-users] ITK and netlab<br></font><br>
Hi Kaveh,<br><br><br>Your first two questions will be better addressed if you post them to<br>the VXL users list.<br><br>(it is a kind way to say that : we don't really know....) :-)<br><br>--<br><br>In the context of ITK, we use VXL mainly for providing the following<br>functionalities<br><br> A) Linear algebra solutions<br> B) Optimization<br><br>most of the methods for (A) and (B) will be provided by vnl throught<br>the vnl_matrix<br>and vnl_vector classes. You will find the most used method under the directory<br><br> Insight/Utilities/vxl/core/vnl/algo<br><br><br>Some of these algorithms are implemented in VXL by making calls to functions<br>provided by blas, while others are provided by lapack.<br><br><br>When we make use of vxl, we rarely expose the internal implementations of the<br>methods. That
is, we never call the blas or lapack routines directly.<br>Instead we<br>do this through the C++ API defined by VXL.<br><br><br>What specific functionalities do you have in mind ?<br><br>Are you looking for Linear Algebra ? or for Optimizations ? or something else ?<br><br><br> Please let us know,<br><br><br> Thanks<br><br><br>--------------------------------------------------------------------------------------------------------<br>On Tue, Mar 31, 2009 at 10:56 AM, Kaveh Kohan <<a ymailto="mailto:kaveh.kohan@yahoo.com" href="mailto:kaveh.kohan@yahoo.com">kaveh.kohan@yahoo.com</a>> wrote:<br>> Dear All,<br>><br>> I have a question about using and linking ITK programs to the netlib<br>> libraries already available in the following folder inside of the ITK<br>> directory tree:<br>><br>> $ITKDIR/Utilities/vxl/v3p/netlib/blas<br>> $ITKDIR/Utilities/vxl/v3p/netlib/lapack<br>>
$ITKDIR/Utilities/vxl/v3p/netlib/linpack<br>> $ITKDIR/Utilities/vxl/v3p/netlib/sparse<br>> $ITKDIR/Utilities/vxl/v3p/netlib/libf2c<br>> ...<br>><br>> Here is my question and I would be thankful if you can help:<br>><br>> 1) Does VXL by default uses blas for its operations or one needs to activate<br>> special flag to activate it? If yes, does anybody know how I can activate<br>> using blas, lapck?<br>><br>> 2) When one calls VNL class, does it use lapack, blas or one needs to set a<br>> flag for it?<br>><br>> 3) Is there any example about using blas, lack inside of itk programs?<br>><br>> Thanks,<br>> Kaveh<br>><br>><br>><br>> _____________________________________<br>> Powered by <a target="_blank" href="http://www.kitware.com">www.kitware.com</a><br>><br>> Visit other Kitware open-source projects at<br><span>> <a target="_blank"
href="http://www.kitware.com/opensource/opensource.html">http://www.kitware.com/opensource/opensource.html</a></span><br>><br>> Please keep messages on-topic and check the ITK FAQ at:<br><span>> <a target="_blank" href="http://www.itk.org/Wiki/ITK_FAQ">http://www.itk.org/Wiki/ITK_FAQ</a></span><br>><br>> Follow this link to subscribe/unsubscribe:<br><span>> <a target="_blank" href="http://www.itk.org/mailman/listinfo/insight-users">http://www.itk.org/mailman/listinfo/insight-users</a></span><br>><br>><br></div></div></div><br>
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