[Getdp] question about--with-scalar-type=complex

Christophe Geuzaine cgeuzaine at ulg.ac.be
Fri Jan 13 10:39:12 CET 2012

On 13 Jan 2012, at 10:28, Jung Thomas wrote:

> Hello,
> I just realized that I have been happily doing time harmonic calculations, using Resolutions of Type ComplexValue,
> using a petsc installation that has been configured without the –with-scalar-type=complex option, obtaining however reasonably looking results,
> I am wondering now – does this flag just enable a perhaps more efficient algorithm, or have I been calculating nonsense?
> Any answer would be higly appreciated, as I am a little scared right now.

Don't be scared ;-)

If you compile with –with-scalar-type=real, GetDP treats real and imaginary parts separately, and uses real arithmetic for all the numerical linear algebra. If you compile with –with-scalar-type=complex, GetDP uses the more efficient complex-arithmetic linear algebra solvers. 


> Actually I would be happy if everything was o.k. without that flag, because then I could continue using BoomerAMG from Hypre, which for me, up to now,
> has been by far the most efficient solver,  but does not support the complex scalar type….
> Best regards,
> Thomas
> Thomas Jung
> Fraunhofer IISB
> 91052 Erlangen
> Germany
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Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science