Dear Barry, Thanks for the quick response. It indeed prints out all of my matrix values, so I need to set a threshold to get a sense of it. You are right that even I have a approximate Jacobian, the solution can converge in a quasi newton way.
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> On Feb 24, 2024, at 10: 50 AM, Yi Hu wrote: > > Dear Barry, > > Thanks for the hint. > > This works for my purpose. I did not need to access my form function value, so I did not call SNESGetFunction()
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Dear Barry, Thanks for the hint. This works for my purpose. I did not need to access my form function value, so I did not call SNESGetFunction() in my callback function. Maybe another small question about Jacobian test. I implemented a matrix-free
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Use SNESSetUpdate() to provide a callback function that gets called by SNES
automatically immediately before each linear solve. Inside your callback use
SNESGetFunction(snes,f,NULL,NULL); to access the last computed value of your
function, from this you can update your global variable.
Barr
Dear PETSc team,
I am using a newtonls snes solver. I know that form residual is invoked
at several locations of the algorithm, first evaluated for the rhs of
ksp solver, then several times for obtaining the optimal step of line
search.
In my problem I have a global variable that is updated
