[petsc-users] need more argument in FormFuction in SNESSetFunction

[Timothée Nicolas]

Hi,

If you want to use other arrays, you can either put them in modules and
then "use" the module at the very top of the subroutine, or create a new
type which can contain anything (scalars, integers, arrays but also more
complex PETSc objects), and put an instance of this type in the place of
your dummy array.

For instance

module types
  type levelcontext
#include "petsc/finclude/petscdmdef.h"

 DM :: da
 PetscScalar :: MyArray(10)

  end type levelcontext
end module types

and then in your main you can do

use types
type(levelcontext) :: ctx

Finally you call SNESSetFunction as

CALL SNESSetFunction(snes,r,FormFunction,ctx,ierr)

Inside SNESSetFunction you can then access your array or your DMDA as
ctx%MyArray, ctx%da etc etc.

Also, in principle I think you should set the context ctx of SNES with
call SNESSetApplicationContext(snes,ctx,ierr)

Best

Timothée


2016-03-26 13:21 GMT+09:00 Josh Lo <ysjosh.lo at gmail.com>:

> Hi,
>
> I am trying to SNES with Fortran.
> In FormFunction in SNESSetFuction, i need to call other subroutine and
> many array to calculate F(x), but seems like SNESSetFunction only allows
> one user-defined array as input argument, say, "dummy" in the next line.
>
> CALL SNESSetFunction(snes,r,FormFunction,dummy,ierr)
>
> How can I pass more than one array through SNESSetFunction to FormFunction?
>
> I am a beginner for PETSc, so the question maybe naive.
>
> Thanks,
> Lo
>
>
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