[petsc-users] Differencing parameter

[Barry Smith]

  I have fixed petsc-dev to never return garbage in this call. Also fixed the other MatMFFD methods to use the compose/query function paradigm

   Barry

On Mar 29, 2011, at 2:35 AM, Jed Brown wrote:

> On Tue, Mar 29, 2011 at 08:07, Kontsantinos Kontzialis <ckontzialis at lycos.com> wrote:
>  When should I call MatMFFDGeth in order to get the differencing parameter?
> I call it after SNESSolve but I get zero for h.
> 
> I suspect you are calling this function on a matrix of the wrong type (and, because this function does not check types properly, returning nonsense bytes that happen to represent a very small floating point value). Try calling
> 
>     ierr = SNESGetJacobian(snes,&mat,0,0,0);CHKERRQ(ierr);
>     ierr = MatMFFDGetH(mat,&h);CHKERRQ(ierr);
>