Thank you for the relevant links! The downside is that there does not seem to be a proposal to allow for more general base types within std::complex, e.g., __float128. This is actually my major complaint (that and fear of unstable complex arithmetic, especially division).
Jack On Tue, Feb 7, 2012 at 1:19 PM, Chetan Jhurani <chetan.jhurani at gmail.com>wrote: > I?ve faced similar issues with std::complex, but the material below,**** > > which is not in the C++ standard, has suppressed my fears. Not**** > > eliminated though.**** > > ** ** > > http://fftw.org/doc/Complex-numbers.html (has a broken link, corrected > below)**** > > http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2002/n1388.pdf**** > > ** ** > > Chetan**** > > ** ** > > *From:* petsc-users-bounces at mcs.anl.gov [mailto: > petsc-users-bounces at mcs.anl.gov] *On Behalf Of *Jack Poulson > *Sent:* Tuesday, February 07, 2012 10:10 AM > *To:* PETSc users list > *Subject:* Re: [petsc-users] one compilation error in PETSc-dev with > enabling GPU and complex number**** > > ** ** > > On Tue, Feb 7, 2012 at 11:29 AM, Matthew Knepley <knepley at gmail.com> > wrote:**** > > On Tue, Feb 7, 2012 at 11:20 AM, recrusader <recrusader at gmail.com> wrote:* > *** > > Whether is it possible to find an efficient mechanism to do the conversion > between std::complex and cusp::complex when the conversion is necessary.** > ** > > ** ** > > That does not matter. This is a compile error. We are not going to change > this right now, and it seems like you are not going**** > > make the necessary changes, so I would say that complex numbers are not > supported with our GPU code right now. The**** > > change would involve using cusp::complex for PetscScalar, and I am not > sure how much work that would entail.**** > > ** ** > > Matt**** > > > Matt, **** > > > You might be interested to hear that the C++03 standard states that "The > effect of instantiating the template complex for any type other than float, > double or long double is unspecified". Thus, complex quad precision with it > is probably a bad idea and, if I'm not mistaken, the standard does not > state that the class must store data in the form > > double real, imag; > > so this could potentially break interfaces (e.g., to BLAS or LAPACK). > Maybe it would be worthwhile to avoid usage of std::complex and > simultaneously fix the compatibility issue with cusp::complex. I recently > ripped std::complex out of Elemental for the above reasons. > > Jack**** > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120207/8413cf33/attachment.htm>
