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dgemv returns wrong results

Posted: Wed Dec 14, 2011 10:01 am
by itabhiyanta

i am using magmablas_dgemv function for calculating a matrix vector product however the results do not seem to match those generated by the magma_dpotrf_gpu (followed by) magma_dpotrs_gpu.

the matrix is really small 8x8. the hardware i am running it on is a C2050.

does anyone face a similar problem? if yes could you suggest what must be done to solve this issue?

kindly help
thanks in advance

Re: dgemv returns wrong results

Posted: Fri Jan 06, 2012 4:39 pm
by mgates3
I'm not sure that I understand your question. Doing gemv( A, x ) yields A*x. Doing potrf( A ) then potrs( A, x ) yields A^{-1}*x, or in Matlab notation, A\x. These two, A*x and A\x, should not be the same.

Can you clarify what are your inputs to each function, and what is the expected output?