Hi all (and probably more specifically Matt ?)
I am trying to understand how the class IDs of a DM field are set, and
can't find it in the documentation.
A little background, I am mimicking
SNES/utils/dmadapt.c/DMAdaptorAdapt_Sequence_Private for a specific case
(I'm trying to build the same kind of metric from a single sensor field,
without all the SNES layer).
I need to compute the gradient of the sensor field, using
DMPlexComputeGradientClementInterpolant, for which I create a DM, to
which I associate a PetscFE, a DS, like in existing code:
PetscFE feGrad
PetscDS probGrad
ierr = PetscFECreateDefault(PetscObjectComm((PetscObject) dmGrad), dim,
coordDim, PETSC_TRUE, NULL, -1, &feGrad);CHKERRQ(ierr);
ierr = PetscDSSetDiscretization(probGrad, f, (PetscObject)
feGrad);CHKERRQ(ierr);
ierr = PetscFEDestroy(&feGrad);CHKERRQ(ierr);
Yet, when I call DMPlexComputeGradientClementInterpolant, I get the
following error:
[0]PETSC ERROR: Unknown discretization type for field 0
I don't fully understand what all these objects are (FE, DS and Field),
and how they are related, where would that be documented ?
And what else do I need to do to make my example work ?
Thanks
--
Nicolas
