> On Nov 19, 2015, at 11:25 AM, Carles Bona <[email protected]> wrote:
> 
> Dear all,
> 
> I would like to add some of my equations before I modify them.

   Please explain what you mean by this. Algebraically exactly what do you want 
to do?


> I haven't found any high level function that would allow me to add rows of a 
> matrix (I am working with a parallel BAIJ). Is there any nice way of doing 
> this?
> 
> I have tried with MatGetRow/MatRestoreRow, but I am struggling a bit to 
> retain the cols and vals, as only one processor can call MatGetRow but if 
> only that processor tries to allocate memory then one gets a segmentation 
> fault. I guess I should allocate enough memory on all processors... 
> 
> If I refrain from storing the cols and vals I need to call MatSetValues 
> before returning the pointer, with a subsequent call to assemblybegin/end for 
> each row, which slows down the code.
> 
> The other option would be to forget about these row additions after the 
> matrix has been filled and try to fill it while taking into account these row 
> additions at the same time. I guess I need to be constantly checking for 
> indices then.
> 
> So, which option (not necessarily mentioned here) would you reccomend?
> 
> Thanks a lot,
> 
> Carles

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