From: David Xu <dxu@my...>  20060305 19:35:59

Steffen, I just tried LAPACK option and got a error: ** On entry to DSYEVD parameter number 8 had an illegal value So, should I try recompile Petsc and Slepc with ARPACK? Could you give me some details on how to do and use ARPACK in libmesh code? Thanks! David On 3/5/06, Steffen Petersen <steffen.petersen@...> wrote: > Hello David, > > I have not seen this error before, but is seems > that there might be a problem with the lapack > installation on your system. > > If your problem is of small size you can also > try the LAPACK eigen solver (in case you LAPACK installation > works fine) to verify your code: > > eigen_system.eigen_solver>set_eigensolver_type(LAPACK); > eigen_system.eigen_solver>set_position_of_spectrum(SMALLEST_REAL); > > > Steffen > > > David Xu schrieb: > > Hi Steffen, > > > > I looked at Slepc online example 6 > > (http://www.grycap.upv.es/slepc/handson/handson6.html) and tried to > > use Lanczos solver with EPS_SMALLEST_REAL option. So I added these 2 > > lines in my libmesh code: > > > > eigen_system.eigen_solver>set_eigensolver_type(LANCZOS); > > eigen_system.eigen_solver>set_position_of_spectrum(SMALLEST_REAL); > > > > This gave the following error: > > > > [0]PETSC ERROR: EPSSolve_LANCZOS() line 411 in src/eps/impls/lanczos/la= nczos.c > > [0]PETSC ERROR: No support for this operation for this object type! > > [0]PETSC ERROR: DSTEVR  Lapack routine is unavailable.! > > [0]PETSC ERROR: EPSSolve() line 58 in src/eps/interface/solve.c > > [0]PETSC ERROR: User provided function() line 280 in > > unknowndirectory/src/numerics/slepc_eigen_solver.C > > > > If I try eigen_system.eigen_solver>set_position_of_spectrum(EPS_SMALLE= ST_REAL); > > The error is: > > ex17.C: In function =E2int main(int, char**)=E2: > > ex17.C:147: error: =E2EPS_SMALLEST_REAL=E2 was not declared in this sco= pe > > > > My question is how to enable Lanczos in my code to compute the > > smallest eigenvalues. I know you said it was unstable sometimes, but > > I'd like to try it on my 1D code so that I can verify my 1D code is > > correct when comparing the results against analytical ones. > > > > Thanks, > > > > David > > 