[petsc-dev] SNESLineSearchApply_BT logic divergence

[Barry Smith]

On Jun 15, 2012, at 11:07 AM, Daniel Lowell wrote:

> I did indeed bypass them.


   Never bypass them!

 
> Ok, thanks.
> 
> 
> On Fri, Jun 15, 2012 at 11:06 AM, Matthew Knepley <knepley at gmail.com> wrote:
> On Sat, Jun 16, 2012 at 12:03 AM, Daniel Lowell <redratio1 at gmail.com> wrote:
> Hey Satish,
> 
> So I'm having an issue with this function: 
> 
> #define PetscObjectComposedDataGetReal(obj,id,data,flag)                            \
> ((((obj)->realcomposedstate && ((obj)->realcomposedstate[id] == (obj)->state))?  \
> (data = (obj)->realcomposeddata[id],flag = PETSC_TRUE) : (flag = PETSC_FALSE)),0)
> 
> Called from VecNorm which is called from SNESLineSearchApply_BT
> 
> I have two examples running one is the vanilla ex14 using my GPU vector and matrix type.  The other example is a variant of ex14test where I am implementing GPU formfunction and formjacobian.
> ex14 vanilla runs through correctly, however ex14test diverges in the logic within VecNorm, specifically line 164:
>  /*
>    * Cached data?
>    */
>   if (type!=NORM_1_AND_2) {
>     ierr = PetscObjectComposedDataGetReal
> ((PetscObject)x,NormIds[type],*val,flg);CHKERRQ(ierr);
>     if (flg) PetscFunctionReturn(0);
>   }
> 
> The ex14 detects there is a "real" part, however the ex14test does not and VecNorm returns. 
> 
> "val" in VecNorm is PetscReal gnorm = fnorm defined in SNESLineSearchApply_BT. 
> For ex14:       val[0]=3.44e-317, val[1]: 0.580
> For ex14test: val[0]=3.44e-317, val[1]: 0.029
> 
> 
> This difference makes SNESLineSearchApply_BT branch into different execution paths.
> 
> I'm not sure where the issue could have come from. Any ideas?
> 
> If you change values in a Vec, you must increment the internal state, since we cache norms.
> The internal functions for array getting do this automatically, so I am not sure why this is
> messing up. Did you bypass them?
> 
>    Matt
>  
> 
> -- 
> Daniel Lowell
> 
> 
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> 
> 
> 
> -- 
> Daniel Lowell
>