On Sat, Jun 25, 2011 at 2:49 PM, NAN ZHAO <zhaonanavril at gmail.com> wrote:
> Dear all, > > I have a question about how to use the ksp in a smart way to solve a linear > system. I had a simple test to generate a random matrix and vector, but I > put only one nonzero value in a row (let's say 1), and in the respect > location of the RHS vector I put a zero. The size of the matrix is kind of > big, I saw petsc some time give unreasonable value at that loaction (it > should be zero or some really small number). I want to know if there is a > way to avoid it? > The problem sounds degenerate. A full rank A with 1 nonzero/row and b = 0 would not have a solution other than 0. What will this tell you? Matt > Thanks > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110625/463c361b/attachment.htm>
