[petsc-users] multiplication of two vetors

[Matthew Knepley]

On Wed, Feb 10, 2016 at 8:06 AM, wen zhao <wen.zhao at outlook.fr> wrote:

> Hello
>
> I have another question about the multiplication of two vector with the
> form
>
> (x) * (x^T), which x is of length n,
>
> That means, the result is a matrix. Is there some functions in Petsc.
>

You do not want to form this matrix since it is dense but very low rank. We
do not have
a separate abstraction for outer product matrices, but it would not be hard
to write. However,
its not clear it would save people much programming, and it increases the
interface size.

  Thanks,

     Matt


> Thanks
>
-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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