Hi Denis. I also don't know how the first method can be implemented. I read the above models in the book By Neto, Peric and Owen “Computational method for plasticity”. They have been computed the determinant of the stiffness matrix during solving the linear system using the classical frontal method. In the frontal method, the linear system is solved by Gauss elimination. Now I am working on the last criterion, however, for my problems the first one will work better.
Regards, Pasha On Monday, January 2, 2017 at 4:43:09 PM UTC+3:30, Denis Davydov wrote: > > Hi Pasha, > > It looks like what you need is to know whether the matrix is > positive-definite or negative-definite. > I don't think there is way to calculate a determinant of an arbitrary huge > sparse matrix such as Epetra_CrsMatrix, that is wrapped in TrilinosWrappers. > I gave a quick look at Epetra_CrsMatrix and, not surprisingly, did not > see anything > https://trilinos.org/docs/dev/packages/epetra/doc/html/classEpetra__CrsMatrix.html > > . > > I wonder if it is possible to get around the issue from local stiffness > matrices? > I would probably dig further into literature to see how (1) is implemented. > > Regards, > Denis. > > On Monday, January 2, 2017 at 8:33:23 AM UTC+1, [email protected] wrote: >> >> Dear all >> >> I am working on a arc-length-Newton-Raphson solution algorithm. To derive >> the arc-length method, I allow incremental load factor ∆λ to become a >> variable and redefine the residual equation. I used cylindrical arc-length >> method. In this method the iterative load factor is normally chosen as the >> solution to the quadratic equation. The success of the path-following >> technique depends crucially on the choice of the appropriate sign for the >> iterative load factor. Some criteria are listed below: >> 1) Stiffness determinant. Follow the sign of the stiffness determinant >> 2) Incremental work. Follow the sign of the predictor work increment >> 3) Secant path. >> Procedure 1 is widely used in commercial finite element codes and works >> well in the absence of bifurcations. Therefor, I need the sign of the >> determinant of the global tangent stiffness matrix which is >> a dealii::LinearAlgebraTrilinos::MPI::BlockSparseMatrix. How I can compute >> this sign? >> >> Regards, >> Pasha >> > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
