[petsc-users] Questions concerning ex12.c

[Jones,Martin Alexander]

How do we input an auxillary field so that we can use the a[] array in the f0_u 
function in ex12.c ?

Void f0_u(const PetscScalar u[], const PetscScalar gradU[], const PetscScalar 
a[], const PetscScalar gradA[],const PetscReal x[], PetscScalar f0[])

I would like a=constant within a bounded volume and a=0 outside the bounded 
volume.

Any help on this is much appreciated. Thanks.

Martin Jones