Re: [ViennaCL-devel] Computing A += prod(B,C)

[Karl R. <ru...@iu...>]

Hello again,

I've justed pushed the following changes to the sourceforge-repository:
* operator+= and operator-= no longer create temporaries
* A = prod(B,C) does not fail if there is garbage in A

Best regards,
Karli


On 07/29/2012 03:59 PM, Philippe Tillet wrote:
> Hello everybody !
>
> I'll inaugurate this mailing list with a little question.
> I have not seen any kernel for computing the operation A += prod(B,C) .
> Does this mean that this operation is done doing :
>
> tmp = prod(B,C)
> a+=tmp
>
> ?
>
> For computing the multi_matrix ( project i'm working on, matrix composed
> of multiple handles, to solve the CL_MAX_ALLOCABLE_MEMORY and the multi
> devices issue), I need to do several updates of this kind, in a block
> layout. For a 2*2 block layout :
>
> C(0,0).clear();
> =>
> C(0,0) += prod( A(0,0), B(0,0) )
> =>
> C(0,0) += prod( A(0,1), B(1,0) )
>
> C(0,1).clear();
> =>
> C(0,1) += prod( A(0,0), B(0,1) )
> =>
> C(0,1) += prod( A(0,1), B(1,1) )
>
> ...
> ...
>
> This "sort-of-rank-1-update approach" is a special case of the SUMMA
> Algorithm (OpenCL doing the memory transfers in the back ground, for now
> at least) and seems to be efficient from a memory point of view. Using
> another approach would lead to both a huge memory consumption and
> significant memory transfers...
>
> Is there any way of doing so in ViennaCL ?
>
> Best regards !
> Phil
>
>
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