[petsc-users] TAO: armijo condition not fulfilled

[Jason Sarich]

Hi Andreas,

Yes it looks like a bug that the reason is never set, but the line should
still terminate. Is the problem you are having with the line search itself,
or is it failing because you are checking this ls->reason directly?

Jason Sarich


On Thu, Jun 11, 2015 at 9:53 AM, Andreas Mang <andreas at ices.utexas.edu>
wrote:

> Hi guys:
>
> I have a problem with the TAO Armijo line search (petsc-3.5.4). My
> algorithm works if I use the More & Thuente line search (default). I have
> numerically checked the gradient of my objective. It’s correct. I am happy
> to write a small snippet of code and do an easy test if you guys disagree,
> but from what I’ve seen in the line search code it seems obvious to me that
> there is a bug. Am I missing something or are you not setting
>
> ls->reason
>
> to
>
> TAOLINESEARCH_SUCCESS
>
> if the Armijo condition is fulfilled (TaoLineSearchApply_Armijo in
> armijo.c; line 118 - 302)?!
>
> It seems to me that ls->reason is and will remain to be set to
>
> TAOLINESEARCH_CONTINUE_ITERATING
>
> if everything works (i.e. I don’t hit one of the exceptions). Does this
> make sense? If not I’ll invest the time and put together a simple test case
> and, if that works, continue to check my code.
>
> /Andreas
>
>
>
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