On 7/30/19 1:28 PM, Daniel Garcia-Sanchez wrote: > > I did 3 test which gave the same solution: > > * Original mesh. determinant(system_matrix) = 6.6e10 > * Move vertex and do not apply constraint. determinant(system_matrix) > = 6e11 > * Move vert and apply constraint. det(system_matrix) = 1.2e12
You can't compute the determinant for anything but quite small matrices. It's not a numerically stable operation. The only way to determine whether a matrix is singular is to compute all eigenvalues and see whether one or more are "small" compared to the size of the other eigenvalues. Can you do that for the matrices you have, and plot the eigenvalues in the same plot? Is there a qualitative difference? Best W. -- ------------------------------------------------------------------------ Wolfgang Bangerth email: [email protected] www: http://www.math.colostate.edu/~bangerth/ -- 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/7afaba23-6a4d-8254-cee8-8401c3a8eec2%40colostate.edu.
