On Thu, Dec 19, 2013 at 4:26 PM, Que Cat <[email protected]> wrote:
> Hello, > > I use SNES to solve the non linear coupled equations. I have checked the > hand-coded jacobian with -snes_type test and received the result: > Norm of matrix ratio 1.39606e-23 difference 1.53372e-14 (user-defined > state) > Norm of matrix ratio 3.03157e-10 difference 0.33305 (constant state -1.0) > Norm of matrix ratio 3.03157e-10 difference 0.33305 (constant state 1.0) > It said that " if the ratio is O(1.e-8), the hand-coded Jacobian is > probably correct." What is the second paramenter "difference 1.53372e-14 > ...."? Does it play any role in checking the accuracy of hand-coded > jacobian? > It appears that your Jacobian is correct, or at least has an error that is much smaller than most of the elements. > The SNES solver for failed with the reason -6 "the line search failed". I > tried with all other line search method stated in the PETSC manual, but > they all failed. > Do you know that the problem has a solution. Its possible that there is no real solution. Matt > I tried to figure out what is wrong with my code? Could you please give me > any recommendation to direct me how to check my code? I appreciate your > help. > > QUe > > -- 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
