> On Feb 7, 2020, at 7:44 AM, Hao DONG wrote:
>
> Thanks, Barry, I really appreciate your help -
>
> I removed the OpenMP flags and rebuilt PETSc. So the problem is from the BLAS
> lib I linked?
Yes, the openmp causes it to run in parallel, but the problem is not big
enough and the machi
Fande Kong writes:
> Thanks, Matt,
>
> It is a great paper. According to the paper, here is my understanding: for
> normal matrices, the eigenvalues of the matrix together with the
> initial residual completely determine the GMRES convergence rate. For
> non-normal matrices, eigenvalues are NOT t
On Fri, 7 Feb 2020 at 19:15, Fande Kong wrote:
> Thanks, Matt,
>
> It is a great paper. According to the paper, here is my understanding: for
> normal matrices, the eigenvalues of the matrix together with the
> initial residual completely determine the GMRES convergence rate. For
> non-normal mat
On Fri, Feb 7, 2020 at 11:43 AM Victor Eijkhout
wrote:
>
>
> On , 2020Feb7, at 12:31, Mark Adams wrote:
>
> BTW, one of my earliest talks, in grad school before I had any real
> results, was called "condition number does not matter”
>
>
> After you learn that the condition number gives an _upper
Thanks, Matt,
It is a great paper. According to the paper, here is my understanding: for
normal matrices, the eigenvalues of the matrix together with the
initial residual completely determine the GMRES convergence rate. For
non-normal matrices, eigenvalues are NOT the relevant quantities in
determ
On Fri, Feb 7, 2020 at 1:43 PM Victor Eijkhout
wrote:
>
>
> On , 2020Feb7, at 12:31, Mark Adams wrote:
>
> BTW, one of my earliest talks, in grad school before I had any real
> results, was called "condition number does not matter”
>
>
> After you learn that the condition number gives an _upper_
On , 2020Feb7, at 12:31, Mark Adams mailto:mfad...@lbl.gov>>
wrote:
BTW, one of my earliest talks, in grad school before I had any real results,
was called "condition number does not matter”
After you learn that the condition number gives an _upper_bound_ on the number
of iterations, you lea
On Thu, Feb 6, 2020 at 8:07 PM Alexander Lindsay
wrote:
> It looks like Fande has attached the eigenvalue plots with the real axis
> having a logarithmic scale. The same plots with a linear scale are attached
> here.
>
> The system has 306 degrees of freedom. 12 eigenvalues are unity for both
> s
On Thu, Feb 6, 2020 at 8:07 PM Alexander Lindsay
wrote:
> It looks like Fande has attached the eigenvalue plots with the real axis
> having a logarithmic scale. The same plots with a linear scale are attached
> here.
>
> The system has 306 degrees of freedom. 12 eigenvalues are unity for both
> s
On Thu, Feb 6, 2020 at 7:37 PM Fande Kong wrote:
> Hi All,
>
> MOOSE team, Alex and I are working on some variable scaling techniques to
> improve the condition number of the matrix of linear systems. The goal of
> variable scaling is to make the diagonal of matrix as close to unity as
> possible
This error appears when computing the B-norm of a vector x, as sqrt(x'*B*x).
Probably your B matrix is semi-definite, and due to floating-point error the
value x'*B*x becomes negative for a certain vector x. The code uses a tolerance
of 10*PETSC_MACHINE_EPSILON, but it seems the rounding errors
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