Jose,
Thank you so much for looking at my code and suggesting the
VecScatterCreateToZero() idea. This has fixed the nan problem, and my
eigenvectors are looking much better now.
Best regards,
Patrick
On 9/9/22 01:21, Jose E. Roman wrote:
First, I would suggest that you add preallocation
First, I would suggest that you add preallocation for SeqAIJ matrices, in this
way you can run the program with 1 process:
MatSeqAIJSetPreallocation(A, 0, d_nnz);
MatSeqAIJSetPreallocation(B, 0, d_nnz);
With 1 process, the output files are correct. But with more than one process
the
I have attached a minimal example, although it does have a dependency on
the GSL library (sorry for this). The script mwe.sh shows how I am
running the program with the various command line arguments. The program
will write the computed eigenvectors to an output file called 'evec' in
GNU
It looks like my problem may be in using the older gcc 7.5.0 compiler.
The nans seem to go away when I compile petsc/slepc and my code on a
newer gcc 11.2 compiler.
Also, the petsc/slepc "make check" tests have errors on gcc 7.5 which
disappear on 11.2.
On 9/7/22 01:20, Jose E. Roman wrote:
You can run with -fp_trap to have the program stop as soon as the first Nan
or Inf appears, this can help track down why it is happening. In a debugger you
can also set the debugger to trap on floating point exceptions (syntax is
debugger dependent) to focus in on where it first happens.
> El 7 sept 2022, a las 6:18, Patrick Alken
> escribió:
>
> I sometimes get Nan output values in computed eigenvectors for the
> generalized symmetric eigenvalue problem produced by slepc. Is this a known
> issue, and is it related to the conditioning of the matrix pair (A,B)? Is
> there
I sometimes get Nan output values in computed eigenvectors for the
generalized symmetric eigenvalue problem produced by slepc. Is this a known
issue, and is it related to the conditioning of the matrix pair (A,B)? Is
there some way to compute a "condition number" of the matrix pair ahead of
time
