Hi Sumit,

 > Bah :) Looks like I am the first one to ask about this. Yeah, that would
> be helpful (at least int and long)

Charles opened up an issue for tracking purposes:
https://github.com/viennacl/viennacl-dev/issues/153


> The second one is moot. So, if CSR is not supported for Column-Major
> matrices, then the only way to go about would be to implicitly cast away
> the Colum -major and make it row-major. Thus, something like this in VCL
> Eigen: Storage orders
> <http://eigen.tuxfamily.org/dox/group__TopicStorageOrders.html>
>       
> Would be helpful without having to create intermediates.

Well, this is a matter of data-structures, so implicit casts will not be 
enough. Explicit transpositions are, unfortunately, costly.


> Also, I encountered another problem: One of my matrix multiplications
> returned all zeros. When I tried to copy an all-zero matrix to the host
> VCL threw an exception in the copy sequence. I think the correct way to
> do this would be:
> a.) Not do any matrix multiplication if all elements are zeros
> b.) If done, then it should fill up the matrix with zeros and return it
> without throwing an assertion.

This sounds like this could also be a bug. What was the matrix size?

Best regards,
Karli



> ------------------------------------------------------------------------
> *From:* Karl Rupp <[email protected]>
> *To:* Sumit Kumar <[email protected]>
> *Cc:* "[email protected]"
> <[email protected]>
> *Sent:* Monday, August 3, 2015 1:23 AM
> *Subject:* Re: [ViennaCL-devel] ViennaCL reductions
>
> Hi Sumit,
>
>  > I was trying to run sparse matrix multiplication, but one of my explicit
>  > template typedefs had Int. After some digging, I found out that CSR only
>  > supported Float or double. Is there any reason for this? Can we also
>  > have support for other templates? (like int ?)
>
> It is technically possible, but we haven't implemented it yet. After 5
> years you are the first to even ask for it ;-)
>
>
>  > Another thing would be the alignment order. Suppose I have a Row-major
>  > Sparse Eigen matrix, then I can copy it to a (Row-Major ?) VCL
>  > compressed matrix. What about a column-major sparse Eigen matrix?
>
> If you can point me to a fast, massively parallel column-major
> matrix-vector multiplication routine, I look into it. However, as far as
> I know, there is no such routine for general sparse matrices, hence it
> does not make sense for us to support it.
>
> Best regards,
> Karli
>
>
>
>
>
>
>  > ------------------------------------------------------------------------
>  > *From:* Karl Rupp <[email protected] <mailto:[email protected]>>
>  > *To:* Sumit Kumar <[email protected] <mailto:[email protected]>>
>  > *Cc:* "[email protected]
> <mailto:[email protected]>"
>  > <[email protected]
> <mailto:[email protected]>>
>  > *Sent:* Friday, July 31, 2015 9:04 PM
>  > *Subject:* Re: [ViennaCL-devel] ViennaCL reductions
>  >
>  > Hi Sumit,
>  >
>  >  > I am aware that Eigen can do it for its matrices and I am also aware
>  >  > that VCL cannot do it natively. My question was this:
>  >  > In your example of interfacing with Eigen, you have shown a VCL dense
>  >  > matrix interfacing with an Eigen dense matrix. Do you have any example
>  >  > of interfacing an Eigen Sparse matrix with a VCL dense matrix?
>  >
>  > No, we don't have this.
>  >
>  >
>  >
>  >
>  > Best regards,
>  > Karli
>  >
>  >
>  >
>  >
>
>
>


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