OK. I 'll try to shed some light on this when I have a MUMPS's guy around !... And try to ask to get that exposed if possible (?). I guess the answer is the same for getting L and U from LU factorisation (using MUMPS).
What about the same question when using any other package ? (say SUPERLU) Franck ----- Mail original ----- > De: "Hong" <[email protected]> > À: "Franck Houssen" <[email protected]> > Cc: "For users of the development version of PETSc" <[email protected]> > Envoyé: Jeudi 24 Août 2017 17:00:40 > Objet: Re: [petsc-dev] How to get L and D from cholesky factorisation ? > mumps stores LDLt using its private internal data structure, which is not > exposed to user and can be used only via mumps API. > Either ask mumps developer about it or use a debugger to step into mumps > source code. > Hong > On Thu, Aug 24, 2017 at 9:46 AM, Franck Houssen < [email protected] > > wrote: > > How to get L (as a Mat) and D (probably as a Vec) from cholesky > > factorisation > > ? > > > I googled and looked in the doc but didn't find any obvious answer. I am > > not > > sure to get the steps to follow: is there a dedicated example ? > > > To make it short, I have: > > > PCSetType(pc, PCCHOLESKY); // LDLt > > > PCFactorSetMatSolverPackage(pc, "mumps"); > > > PCFactorGetMatrix(pc, &f); > > > MatGetInertia(f, ....); // OK ! > > > Now, I would like to get/see L and D: how to get them ? > > > From petsc/src/ksp/ksp/examples/tutorials/ex52.c, I would say > > MatGetDiagonal(f, D) returns D: correct ? If so, how to get L as well ? > > > A related question would be : how to get L and U from a PCLU factorisation > > ? > > > Franck >
