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Re: Householder solver
Henri Lindén writes:
> I am having problems with the Householder alogithm. Usually this is
> used for overdetermined linear systems, i.e. systems in which m >
> n, where A \in R^{m \times n}. Then how come i.e. the following
> code: yields the following error message:
> gsl: hh.c:41: ERROR: System is underdetermined Aborted
> ???
> Usually the first dimension refers to row dimension and the second
> to columns, which is exactly as things generally are done in
> GSL. Thus my example system should by all means be overdetermined
> with 5 equalities and 3 variables. However the Householder solver
> seems to disagree!
Hi,
Thanks for the bug report.
That code looks to be a bit broken. It is only working for M=N and
gives the wrong message for M>N.
Maybe somebody on the list could volunteer to fix it (??) (also to
make it take a workspace argument of size N for the column norms
instead of allocating memory internally).
In the meantime I'd recommend using the QR or SVD routines for
overdetermined systems instead.
regards
--
Brian Gough
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