Hi Karli,
Thank you very much, you nailed it! I also found the following
documentation (I do not why I have not found it before):
http://viennacl.sourceforge.net/doc/manual-custom-contexts.html
Hence, It is time to try to implement truly incompressible SPH in
AQUAgpusph!
Best wishes,
Pepe
2016-03-30 22:05 GMT+02:00 Karl Rupp <r...@iue.tuwien.ac.at>:
> Hi Jose,
>
> > (Is it Karl or Karli?)
>
> feel free to pick your favorite (just like Jose/Pepe) :-)
>
>
> Thanks for your quick answer! I should further investigate. However, I
>> could not find how to execute an exclusive_scan() without downloading
>> the number of elements per row from the GPU to the host.
>>
>
> exclusive_scan() is also available for vectors (more precisely: the base
> class vector_base<>):
>
> https://github.com/viennacl/viennacl-dev/blob/master/viennacl/linalg/vector_operations.hpp#L1272
>
> Here is an example of how to wrap a host buffer in a vector_base object in
> order to call exclusive_scan:
>
> https://github.com/viennacl/viennacl-dev/blob/master/viennacl/linalg/host_based/amg_operations.hpp#L1444
>
> (the OpenCL version works similarly - either provide your own OpenCL
> cl_mem buffer, or use the memory handle from the compressed_matrix).
>
> Best regards,
> Karli
>
>
>
>
>
>
> 2016-03-29 22:24 GMT+02:00 Karl Rupp <r...@iue.tuwien.ac.at
>> <mailto:r...@iue.tuwien.ac.at>>:
>>
>> Hi Jose,
>>
>> > I have been looking for documentation regarding how to handle a
>> matrix
>>
>> (sparse) in an OpenCL kernel. My main objective is to can fill a
>> sparse
>> matrix using an OpenCL kernel.
>>
>> Would it be possible??
>>
>> P.S. I can eventually precompute the matrix and indexes arrays
>> sizes.
>>
>>
>> Yes, that's possible. The typical procedure for doing so is:
>>
>> 1. Compute number of elements per row, store in a buffer
>> 2. Run exclusive_scan() on the buffer to obtain the row-array for
>> the three-array CSR format.
>> 3. Allocate the column index and value array (CSR format)
>> 4. Populate these two arrays with values
>> 5. Pass the arrays to a viennacl::compressed_matrix<>.
>>
>> Instead of 5. you may already start with a
>> viennacl::compressed_matrix<> and operate on the OpenCL buffers
>> directly.
>>
>> There is no ready-to-go example, but the pattern shows up in e.g.
>> the sparse matrix-matrix product
>> (viennacl/linalg/opencl/sparse_matrix_operations.hpp).
>>
>> Best regards,
>> Karli
>>
>>
>>
>>
>
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