Improve Speed of Matrix Multiplication by Taking Advantage of GPUArray

I actually want to improve the speed of the multiplication of matrix A (m-by-n) and vector x (n-by-1) using GPUArray. Using:

   gpuA = gpuArray(A);
   gpux = gpuArray(x);
   gpuC = gpuA * gpux
   C = gather(gpuC)

didn't give me the needed improvement in speed. Any ideas on how I can achieve this?

[Stephen23]

Why do you need to use arrayfun for this? Matrix multiplication is defined already, without needing arrayfun.

[Chimalume Atuchukwu]

Hi Stephen. Thanks for your contribution. I actually want to improve the speed of the multiplication of matrix A (m-by-n) and vector x (n-by-1) using GPUArray. Using:

gpuA = gpuArray(A);
gpux = gpuArray(x);
gpuC = gpuA * gpux
C = gather(gpuC)
didn't give me the needed improvement in speed

Any ideas on how I can achieve this?

[Azzi Abdelmalek]

The question is not clear

[Chimalume Atuchukwu]

Hi Azzi. Thanks for your contribution. I have edited the question to make it clearer. Any assistance you can offer me will be highly appreciated.

[Edric Ellis]

How large is A? What GPU device do you have? Also, note that ideally you'd compare timings for only the matrix multiplication portion - you shouldn't time the data transfers too as you shouldn't need to keep transferring data. I would compare:

timeit(@() A * x);

against

gputimeit(@() gpuA * gpux);

On my K20 GPU I see break-even when A is about 1000x1000.