Re: [petsc-dev] Broken MatMatMult_MPIAIJ_MPIDense

[Jose E. Roman via petsc-dev]

> El 22 sept 2019, a las 19:11, Smith, Barry F. <bsm...@mcs.anl.gov> escribió:
> 
>   Jose,
> 
>     Thanks for the pointer. 
> 
>     Will this change dramatically affect the organization of SLEPc? As noted 
> in my previous email eventually we need to switch to a new API where the 
> REUSE with a different matrix is even more problematic.
> 
>      If you folks have use cases that fundamentally require reusing a 
> previous matrix instead of destroying and getting a new one created we will 
> need to think about additional features in the API that would allow this 
> reusing of an array. But it seems to me that destroying the old matrix and 
> using the initial call to create the matrix should be ok and just require 
> relatively minor changes to your codes?
> 
>  Barry

We use MatDensePlaceArray() to plug an array into matrix C before MatMatMult(). 
If we cannot do this, we will have to copy from the internal array of the 
result C to our array.

Would the following sequence work?
MatMatMultSymbolic()
MatDensePlaceArray()
MatMatMultNumeric()

Jose