[petsc-users] How to view petsc array?

[TAY wee-beng]

On 19/8/2015 4:58 PM, Dave May wrote:
>
>
> On 19 August 2015 at 10:54, TAY wee-beng <zonexo at gmail.com 
> <mailto:zonexo at gmail.com>> wrote:
>
>
>     On 21/7/2015 7:28 PM, Matthew Knepley wrote:
>>     On Tue, Jul 21, 2015 at 1:35 AM, TAY wee-beng <zonexo at gmail.com
>>     <mailto:zonexo at gmail.com>> wrote:
>>
>>         Hi,
>>
>>         I need to check the contents of the array which was declared
>>         using:
>>
>>         PetscScalar,pointer ::
>>         u_array(:,:,:),v_array(:,:,:),w_array(:,:,:),p_array(:,:,:)
>>
>>         I tried to use :
>>
>>         call PetscViewerASCIIOpen(MPI_COMM_WORLD,"pres.txt",viewer,ierr)
>>
>>         call VecView(p_array,viewer,ierr)
>>
>>         or
>>
>>         call MatView(p_array,viewer,ierr)
>>
>>         call PetscViewerDestroy(viewer,ierr)
>>
>>         but I got segmentation error. So is there a PETSc routine I
>>         can use?
>>
>>
>>     No. Those routines work only for Vec objects. You could
>>
>>      a) Declare a DMDA of the same size
>>
>>      b) Use DMDAVecGetArrayF90() to get out the multidimensional array
>>
>>      c) Use that in your code
>>
>>      d) Use VecView() on the original vector
>
>     Hi,
>
>     Supposed I need to check the contents of the u_array which was
>     declared using:
>
>     PetscScalar,pointer :: u_array(:,:,:)
>
>     call
>     DMDACreate3d(MPI_COMM_WORLD,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,size_x,size_y,&
>
>     size_z,1,PETSC_DECIDE,PETSC_DECIDE,1,stencil_width,lx,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,da_u,ierr)
>
>     call DMDAVecGetArrayF90(da_u,u_local,u_array,ierr)
>
>     call PetscViewerASCIIOpen(MPI_COMM_WORLD,"u.txt",viewer,ierr)
>
>     call VecView(array,viewer,ierr)
>
>
>
> The first argument of VecView must be of type Vec (as Matt noted).
> It looks you are passing in an array of PetscScalar's.

Oh so should it be:

Vec u_global,u_local

call 
DMDACreate3d(MPI_COMM_WORLD,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,size_x,size_y,&

size_z,1,PETSC_DECIDE,PETSC_DECIDE,1,stencil_width,lx,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,da_u,ierr)

call DMDAVecGetArrayF90(da_u,u_local,u_array,ierr)

call PetscViewerASCIIOpen(MPI_COMM_WORLD,"u.txt",viewer,ierr)

call VecView(u_local,viewer,ierr)

call PetscViewerDestroy(viewer,ierr)
>
>
>     call PetscViewerDestroy(viewer,ierr)
>
>     Is this the correct way?
>>
>>        Matt
>>
>>
>>         -- 
>>         Thank you
>>
>>         Yours sincerely,
>>
>>         TAY wee-beng
>>
>>
>>
>>
>>     -- 
>>     What most experimenters take for granted before they begin their
>>     experiments is infinitely more interesting than any results to
>>     which their experiments lead.
>>     -- Norbert Wiener
>
>

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