[Numpy-discussion] Construct symmetric matrix

David Cournapeau cournape@gmail....
Sat Apr 4 23:18:44 CDT 2009

On Sun, Apr 5, 2009 at 11:17 AM, Pierre GM <pgmdevlist@gmail.com> wrote:
> All,
> I'm trying to build a relatively complicated symmetric matrix. I can
> build the upper-right block without pb. What is the fastest way to get
> the LL corner from the UR one ?
> Thanks a lot in advance for any idea.

I may be missing something, but why not building it from scratch + a
couple of elementary operations ? Is it too slow ? For example:

# Assuming the lower part of a is zero before the operation
a + a.T - np.diag(a.diagonal())


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