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[Lapack] need your help about rank-k updating

please see answer on forum

On Thu, 4 Mar 2010, chxyike@Domain.Removed wrote:

Dear Sir/Madam,

I am a Ph.D. candidate in TU, Munich. I have a question about rank-k
updating. Making use of the subroutine 'dsyrk', one can update the symmetric
matrix with only half of the matrix is updated. But with this subroutine,
the other half part, which is not referenced, is still in the memory, of the
case which I want to avoid.

My question is, if I want to update a matrix like C=alfa*A'*A + C, and C is
a m-by-m matrix in packed symmetric storage, A is a n by m matrix, how can I
implement this operation with BLAS or Lapack library, with high performance.

I know that one can use 'dspr' to realize this updating, but since the Blas
level 1 operation is less efficient than level 3, I hope there are some ways
to improve the computation speed.

Best regards

Weiyong YI

D-80290 Muenchen
Tel: (+49)-89-289-23185

e-mail: ? ? ? chxyike@Domain.Removed

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