[petsc-users] TAO: armijo condition not fulfilled

[Andreas Mang]

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