[petsc-users] Error in vec/vec/examples/tutorials/ex19.c

[Smith, Barry F.]

> On Nov 30, 2018, at 1:30 PM, Sajid Ali via petsc-users <petsc-users at mcs.anl.gov> wrote:
>
> Hi,
>
> I tried running ex19.c and I get the following error (I added a small snippet to print the local size on rank0 as well) :
>
> [sajid at xrm temp]$ mpirun -np 2 ./ex19
> local_sizes : 3 4
> [1]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
> [1]PETSC ERROR: Arguments are incompatible
> [1]PETSC ERROR: Incompatible vector local lengths parameter # 1 local size 3 != parameter # 2 local size 2
> [1]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
> [1]PETSC ERROR: Petsc Release Version 3.10.2, unknown
> [1]PETSC ERROR: ./ex19 on a  named xrm by sajid Fri Nov 30 13:28:36 2018
> [1]PETSC ERROR: [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
> [0]PETSC ERROR: Arguments are incompatible
> [0]PETSC ERROR: Incompatible vector local lengths parameter # 1 local size 3 != parameter # 2 local size 4
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
> [0]PETSC ERROR: Petsc Release Version 3.10.2, unknown
> [0]PETSC ERROR: ./ex19 on a  named xrm by sajid Fri Nov 30 13:28:36 2018
>
> Does this mean that PETSC_DECIDE is inconsistent between two calls in the same file ?

   No. The reason for the error is a bug in the code. The x1 vector has a block size of 1 hence when it is divided among two processes it gets 3 entries on each process. The x2 vector has a block size of 2 so when it is divided among two processes it gets 4 entries on the first process and 2 on the second. The call to VecCopy() does not work because the two vectors have different layouts.

   I have attached a fixed version of the code (that does not copy from x1 to x2).

     Barry



>
> Thank You,
> Sajid Ali
> Applied Physics
> Northwestern University

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20181130/14c2a670/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ex19.c
Type: application/octet-stream
Size: 5225 bytes
Desc: ex19.c
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20181130/14c2a670/attachment.obj>