[petsc-dev] KSP accepts mismatched sizes between Mat and PC

[Smith, Barry F.]

Normally they need to be the same, but not always. For KSPLSQR the A matrix may be rectangular but the B matrix is A^TA which is square. This special case is why we don't do error checking.

    Barry


> On Apr 16, 2018, at 1:04 PM, Alp Dener <alp.dener at gmail.com> wrote:
> 
> Hi Barry,
> 
> While I was working on some active-set related stuff in TAO, I discovered that I can call KSPSetOperators() with differently sized Mat and PC objects without getting any errors or warnings about the size mismatch. Note that my Mat object is explicit, but the PC object is a MATSHELL. Is this intended behavior, or is it a bug? 
> 
> —
> Alp Dener