## Matrix Vector multiplication

Open discussion for MAGMA library (Matrix Algebra on GPU and Multicore Architectures)
Volodimir
Posts: 10
Joined: Fri Jun 29, 2018 2:52 pm

### Matrix Vector multiplication

Hello,

I am new to MAGMA, have a couple of questions regarding availability of functions:

1. in CUDA there is a

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``cublas<t>dgmm()``
function allowing to perform element-wise matrix-matrix multiplication
2. Likewise, there is a function

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`` cublasGetMatrix``
allowing to extract subarray from array.

Question - how I can implement these using MAGMA?

Thanks,

Volodimir

mgates3
Posts: 902
Joined: Fri Jan 06, 2012 2:13 pm

### Re: Matrix Vector multiplication

1) MAGMA doesn't have an element-wise multiply. However, you can still call the cublas function while using MAGMA.

2) MAGMA has:
magma_*setmatrix
magma_*getmatrix
magma_*setmatrix_async
magma_*getmatrix_async
where * is one of s, d, c, z, or i for single, double, single-complex, double-complex, or integer, respectively. See
http://icl.cs.utk.edu/projectsfiles/mag ... _comm.html
for all communication-related routines.

Unlike cublasGetMatrix, the MAGMA routines do not require passing sizeof the elements.

-mark

Volodimir
Posts: 10
Joined: Fri Jun 29, 2018 2:52 pm

### Re: Matrix Vector multiplication

Mark,

I am having difficulties in calling cublas functions while using MAGMA, as I am using complex arrays, and there is no straightforward conversion between MAGMA complex types magmaFloatComplex (or magmaDoubleComplex) and cuComplex (or cuDoubleComplex) in CUDA. Or did I miss something?

Thanks,
Volodimir

mgates3
Posts: 902
Joined: Fri Jan 06, 2012 2:13 pm

### Re: Matrix Vector multiplication

magmaFloatComplex is a typedef of cuFloatComplex. It shouldn't need a conversion. See include/magma_types.h:

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``````    typedef cuDoubleComplex magmaDoubleComplex;
typedef cuFloatComplex  magmaFloatComplex;
``````
Nonetheless, if you need a conversion, just do a cast using a pointer. E.g., to convert between std::complex and magmaComplex:

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``````  std::complex<float> alpha;
std::complex<float> *A;
magmaFloatComplex alpha2 = *((magmaFloatComplex*) &alpha);
magmaFloatComplex *A2 = (magmaFloatComplex*) A;
``````
-mark