[SciPy-user] solve for symetric matrix ?

Nils Wagner nwagner at iam.uni-stuttgart.de
Thu Apr 26 07:31:53 EDT 2007


Joachim Dahl wrote:
>
>
> On 4/26/07, *fred* <fredmfp at gmail.com <mailto:fredmfp at gmail.com>> wrote:
>
>     Hi,
>
>     I use scipy.linalg.solve() to solve Au=b, where A is symetric (and
>     diagonal filled with 0).
>
>
> If the diagonal is 0, then the matrix is not definite (so, neither is
> -A)...
>
>
>
I missed the main information (zero diagonal)
Are you aware of a simple proof that a symmetric matrix with zero
diagonal entries is indefinite ?

Anyway it would be great if scipy has a solver for symmetric indefinite
systems e.g. the LAPACK routine
http://www.netlib.org/lapack/double/dsysv.f

AFAIK, this subroutine is currently not available via linalg.flapack.

Nils

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