Hi, > Thanks for the hints! Right as you were writing, I have implemented > now a solution via matrix_range which already performs really well. I > guess there wouldn't be any difference in performance between > viennacl::column and some matrix_range solution, right?
viennacl::column() might be faster for large matrices because of the way threads are assigned. I guess that most of your execution time is spent elsewhere, so it's probably not worth optimizing further... Best regards, Karli > On Thu, Dec 12, 2013 at 2:49 PM, Karl Rupp <r...@iue.tuwien.ac.at> wrote: >> Hi Albert, >> >> >>> I thought that a good way to get good performance is to formulate all >>> >>> the calculations somehow vectorized but I'm not sure if I have chosen >>> the best way because the code performs badly. The matrices are big, >>> about 10k \times 10k in size. >> >> >> This is correct, provided that the vectorization is not carried out via >> adding a lot of operations by zeros. >> >> >> >>> My code is below. Maybe you can give me some suggestions about how to >>> do that fast. Basically, in `mat_column_mult`, I want to multiply a >>> certain column of a matrix. Currently, I multiply with 0, maybe that >>> is a special case where I can do even faster. In >>> `layerActivity_addBiasTerm`, I want to add a left scalar column to a >>> matrix. >> >> >> The issue in the code are the matrix-matrix multiplications, even though you >> only want to scale columns. For such cases you can use the new column() >> function to extract a column from a matrix and scale that. In-place >> operations are supposed to work, so you can directly write >> viennacl::column(A, 7) *= factor; >> Have a look here: >> https://github.com/viennacl/viennacl-dev/blob/master/tests/src/matrix_vector.cpp#L235 >> on how to use it. As with most functionality in ViennaCL, it's basically the >> same as in Boost.uBlas. For this to compile, however, you need to use the >> developer version from GitHub (https://github.com/viennacl/viennacl-dev) or >> wait a few more days until the 1.5.0 release is finally out. :-) >> >> Best regards, >> Karli >> ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ ViennaCL-devel mailing list ViennaCL-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/viennacl-devel
