Hi Hong, I more concern about the difference between A1 and A2 is in the order of O(1.e-8) as I run the same code twice. Should it be in the order of machine epsilon?
Khai On Thu, Dec 8, 2016 at 4:54 PM, Hong <[email protected]> wrote: > Khai : >> >> Thanks for your response. The output is not the solution. They are the >> component of the matrix in matlab format. I would expect the difference in >> the order of machine precesion. The difference in solutions in two runs is >> in the order of 1e-5. >> > > If your matrices A1 and A2 have difference of O(1.e-8), then the computed > solution may differ by > Condition_number(A) * machine_epsion. Do you know cond(A)? > > Please alway send your request to petsc-maint. > > Hong > >> >> >> On Dec 8, 2016 4:01 PM, "Hong" <[email protected]> wrote: >> >> Khai : >> Your solution components have values ranging from 1.e+9 to 1.e-8, and the >> values only differ in the order of 1.e-8, which are within computational >> error tolerance. >> I would consider all solutions same within the approximation tolerance. >> >> Hong >> >> Hello, >>> >>> I have problem with matrix assembly for linear solver KSP. I run the the >>> same problem with 4 processors multiple time. Using flag >>> -mat_view ::ascii_matlab to view the matrix. The matrix outputs are not the >>> same during each run. Please see the attached file for the comparison >>> between two runs. I checked all the input for each processor as it calls to >>> MatSetValues ( indices of the matrix and values ) and it's consistent all >>> the time. I also checked the allocation information (with flag -info) and >>> it looks fine. Could you give me an advice how to deal with this issue? >>> Thanks ! >>> >>> Best, >>> Khai >>> >> >> >> >
