[petsc-dev] Issue with SNESComputeJacobian before SNESSetUp

[Lisandro Dalcin]

If you call SNESComputeJacobian before SNESSetUp, the former routine
tries to call KSPSetReusePreconditioner, but the snes->ksp object is
not available yet.

I guess a single call to  SNESGetKSP(snes,&snes->ksp) would be enough
to fix the issue.

Barry, could you review and eventually fix it?

$ cat tmp.py
from petsc4py import PETSc

X = PETSc.Vec().createSeq(2)
F = PETSc.Vec().createSeq(2)
J = PETSc.Mat().createDense([2,2])
J.setUp()

def Fun(snes,x,F): F.assemble()
def Jac(snes,x,J,P): J.assemble()

snes = PETSc.SNES().create()
snes.setFunction(Fun, F)
snes.setJacobian(Jac, J)

snes.computeFunction(X, F)
snes.computeJacobian(X, J)

$ python tmp.py
Traceback (most recent call last):
  File "tmp.py", line 16, in <module>
    snes.computeJacobian(X, J)
  File "SNES.pyx", line 223, in petsc4py.PETSc.SNES.computeJacobian
(src/petsc4py.PETSc.c:136887)
petsc4py.PETSc.Error: error code 85
[0] SNESComputeJacobian() line 2262 in
/home/devel/petsc/dev/src/snes/interface/snes.c
[0] KSPSetReusePreconditioner() line 191 in
/home/devel/petsc/dev/src/ksp/ksp/interface/itfunc.c
[0] Null argument, when expecting valid pointer
[0] Null Object: Parameter # 1


-- 
Lisandro Dalcin
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