Re: [Libmesh-devel] Typo in petsc_matrix.C:72(?) and cout from proc 1

[Roy S. <roy...@ic...>]

On Fri, 27 Aug 2010, John Peterson wrote:

> On Fri, Aug 27, 2010 at 11:36 AM, John Peterson
> <pet...@cf...> wrote:
>> On Fri, Aug 27, 2010 at 11:30 AM, Roy Stogner <roy...@ic...> wrote:
>>>
>>> On Fri, 27 Aug 2010, Johannes A Huber wrote:
>>>
>>>> I was wondering, is it might be possible petsc_matric.C on line 72 (and perhaps in other lines as well, like 139, 142, ...)
>>>> The matrix that is created in these lines is always quadratic (n_global*n_global). I guess, the second argument to MatCreateSeqAIJ should be
>>>> m_global instead of n_global.
>>>
>>> Let me run this by libmesh-devel (Ben Kirk is the one who wrote that
>>> code, and he surely understands it better than I do), but it looks to
>>> me like you're right.  And since libMesh (and, I'd be willing to bet,
>>> all its primary developers) only creates square sparse matrices, we'd
>>> never have noticed a bug that breaks rectangular sparse matrix
>>> creation.
>>
>> I think you're right, especially considering the call to
>> MatCreateMPIAIJ a few lines below which does use m_global.
>>
>> Nice catch!
>
> And fix checked in.

The line 139 and 142 case isn't exactly a "bug", since in that
constructor we really do always want a square matrix, but I changed
them anyway to avoid confusing anyone in years to come.

Speaking of years: this looks like the oldest bug I've ever seen in
libMesh - it was in place in 2003 when the code first went into
version control!
---
Roy