LAPACK Archives

[Lapack] [lapackers] bug in DGEHRD

On Thu, 22 Apr 2010, James Demmel wrote:

There is a permutation that makes this matrix 2x2 block triangular,

Mmm, I can not find this permutation ... I tried symamd and colamd and 
they can not either.

Note that while
does not work,
   V = Q*V;
works ...

Definetley balancing ... I've just remembered that actually you can 
desactivate balancing in eig of matlab, all relative backward errors are 
back to 1e-16 with [V,D]=eig(A,'nobalance');.


<Prev in Thread] Current Thread [Next in Thread>

For additional information you may use the LAPACK/ScaLAPACK Forum.
Or one of the mailing lists, or