On Mon, 12 Feb 2007, Ben Tay wrote: > Hi, > > I'm trying to experiment with using external solvers. I have some questions: > > 1. Is there any difference in speed with calling the external software from > PETSc or directly using them?
There is minor conversion overhead when you use them from PETSc. > > 2. I tried to install MUMPS using --download-mumps. I was prompted to > include --with-scalapack. After changing, I was again prompted to include > --with-blacs. I changed and again I was told the need for > --with-blacs-dir=<directory>. I thought I'm supposed to specify where to > install blacs and entered a directory. But it seems that I need to specify > the location of where blacs is. But I do not have it. So how do I solve > that? Mumps requires blacs & scalapack. So use: --download-blacs=1 --download-scalapack=1 --download-mumps=1 > > 3. I installed some other external packages. I wanted to test their speed at > solving equations. In the manual, I was told to use the runtime option > -mat_type <mattype> -ksp_type preonly -pc_type <pctype> and also -help to > get help msg. However when I tried to issue ./a.out -mat_type superlu > -ksp_type preonly -pc_type lu, nothing happened. How should the command be > issued? I tried to get help by running ./a.out -h what appears isn't what I > want. Did you install PETSc with superlu_dist? If so use '-mat_type superlu_dist' [Note: superlu & superlu_dist are different packages - the first one is sequential - the second one is parallel] Satish > > Thank you very much. Regards. >
