[petsc-users] Creating Local Copy of locked read only Vec

[Andrew Holm]

Hello,

We are working with an application using SNES and having a problem with the SNESFunction f called by SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx).

We would like our SNESFunction(SNES snes,Vec x,Vec f,void *ctx) to be able to modify Vec x each time the function is called, how ever the vector is locked read only. We are running PETSc 3.9.3 with debugging turned on which tells us that Vec x is locked read only.

To get around this, we have tried to make a local copy of the Vec x using VecCopy (x, xCopy). This gave us the error:
[0]PETSC ERROR: Null argument, when expecting valid pointer
[0]PETSC ERROR: Null Object: Parameter # 2


We have also tried using VecDuplicate(vecWithDesiredLayout, &xLocalCopy) and then VecSetValues to fill the xLocalCopy with the values of Vec x. This gave the error:
[0]PETSC ERROR: Object is in wrong state
[0]PETSC ERROR:  Vec is locked read only, argument # 2


Also, we have tried using VecLockPop in PETSc 3.9.3 to overide the the lock however this seems gives a "Vector has been unlocked too many times" error at runtime:
[0]PETSC ERROR: Object is in wrong state
[0]PETSC ERROR: Vector has been unlocked too many times


Any advice on how to make a local, modifiable copy of the locked read only vector? Any and All help is appreciated!

Andy Holm
Aeroscience Engineer
Kratos Defense and Security Solutions
4904 Research Drive
Huntsville, AL 35805