[petsc-users] how to check state of form residual of snes, for solving ksp or line search?

[Yi Hu]

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 every time when 
form residual is called, which is not desired in the context of 
netwonls. Basically, it should be only evaluated for the purpose of rhs 
of ksp (and not in line search). So is it possible to know in which 
context my form residual is used for? Then I can just skip my line of 
updating global variable depending on this condition. If not possible, 
could you suggest a workaround? Or do I need to design a customized line 
search routine?

Thanks for your help.

Best regards,

Yi



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