> On Oct 7, 2020, at 5:02 PM, baikadi pranay <[email protected]> wrote:
>
> Thank you Barry for the response. Just to make sure I understood correctly, I
> do not need to define any attributes to the vectors and it is automatically
> taken care of (both the intent as well as the allocatable attributes). Am I
> correct?
> For the second question, my subroutine should look like this:
> FormFunction(snes,x,f,3,INTEGER_VARIABLE,ierr)
> Is this correct?
>
For example src/snes/tutorials/ex1f.F90
subroutine FormFunction(snes,x,f,dummy,ierr)
use petscsnes
implicit none
SNES snes
Vec x,f
PetscErrorCode ierr
integer dummy(*)
> Thank you in advance.
> Best Regards,
> Pranay.
>
> ᐧ
>
> On Wed, Oct 7, 2020 at 1:26 PM Barry Smith <[email protected]
> <mailto:[email protected]>> wrote:
>
>
> > On Oct 7, 2020, at 1:41 PM, baikadi pranay <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > Hello,
> > I have a few questions regarding FormFunction when using the SNES solvers.
> > I am using Fortran90.
> >
> > 1) I went through the example (ex1f.F90) provided in the documentation that
> > uses Newton method to solve a two-variable system. In the subroutine
> > FormFunction, the first argument is an input vector (x). However in the
> > code, no attributes are specified saying that it is an input argument for
> > the subroutine (i.e. intent attribute is not specified). Is this
> > automatically taken care of or should I be defining the intent attribute in
> > my code ?
>
> We don't currently provide attributes for our Fortran stubs, so it is best
> if you do not mark them in your subroutines.
>
> Yes the x is input only and the f is output only.
>
> > Also, should I use the "allocatable" attribute when defining the vector x?
>
> I am pretty sure no.
>
> > Please comment similarly on the output vector f as well.
> > 2) Should the ctx argument of the subroutine FormFunction be defined as
> > "PETSC_NULL_INTEGER"?
>
> The context is how you convey additional information into FormFunction().
> Should you choose to not use it then in your function you can declare it as a
> integer and simply not use it. If you are calling your FormFunction() from
> Fortran then just pass a meaningless integer as that argument.
> PETSC_NULL_INTEGER is for call PETSc functions that take integer array
> arguments that you are not supplying.
>
> Barry
>
>
>
> >
> > Please let me know if you need any further information.
> >
> > Thank you.
> > Best Regards,
> > Pranay.
>
