Hi Pai, If you’ve got LAPACK installed then the LAPACKFullMatrix <https://dealii.org/current/doxygen/deal.II/classLAPACKFullMatrix.html> class is able to do the job for you. It has several methods implemented to compute eigenvalues, and you’d then use the eigenvalue() <https://dealii.org/current/doxygen/deal.II/classLAPACKFullMatrix.html#a6014c2616803e673873fab0c87cf1718> method to retrieve each eigenvalue.
I hope this helps. Best, Jean-Paul > On 20 Dec 2019, at 04:23, Pai Liu <[email protected]> wrote: > > Hi all, > In my parallel code, I want to solve the eigenvalues of a small matrix (e.g. > 3 by 3) in serial on each processor. > > I know Step-36 depends on MPI communication to create the eigenfunctions and > to solve the problem, BUT I only need to compute the eigenvalues of a small > matrix in serial on each processor. > > So, is there a easy way to do this, perferly with matrix type > FullMatrix<double>? > > Actually I also have a look at the function "EigenInverse > <https://www.dealii.org/current/doxygen/deal.II/classEigenInverse.html#a9b2fb99066b64446e66f764a3500050c> > (SolverControl > <https://www.dealii.org/current/doxygen/deal.II/classSolverControl.html> &cn, > VectorMemory > <https://www.dealii.org/current/doxygen/deal.II/classVectorMemory.html>< > VectorType > &mem, const AdditionalData > <https://www.dealii.org/current/doxygen/deal.II/structEigenInverse_1_1AdditionalData.html> > &data=AdditionalData > <https://www.dealii.org/current/doxygen/deal.II/structEigenInverse_1_1AdditionalData.html>())", > which may be a good choice. > But I do not understand the description of the second parameter "VectorMemory > <https://www.dealii.org/current/doxygen/deal.II/classVectorMemory.html>< > VectorType > &mem", and thus I dont know how to use this solve function. > Maybe someone can show me an example of this function. > > Many thanks in advance. > > -- > The deal.II project is located at http://www.dealii.org/ > <http://www.dealii.org/> > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > <https://groups.google.com/d/forum/dealii?hl=en> > --- > You received this message because you are subscribed to the Google Groups > "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/bfbea22e-6525-436a-aee6-0b073a1692a6%40googlegroups.com > > <https://groups.google.com/d/msgid/dealii/bfbea22e-6525-436a-aee6-0b073a1692a6%40googlegroups.com?utm_medium=email&utm_source=footer>. -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/8FE6BC63-7FFE-499A-B860-7593089D6B38%40gmail.com.
