Fit Status = 'CALL LIMIT' and 'NOT POSDEF'

Dear all

Hello,

Can I ask some questions?

I’m doing fit with user defined function with 5 parameters.
When I do the fit, root said
’STATUS = CALL LIMIT’ and ERROR MATRIX UNCERTAINTY 17.3 per cent(sometimes 2%, 50%…etc).
So I put
ROOT::Math::MinimizerOptions::SetDefaultMaxFunctionCalls(10000);
in my code, and now root says
’STATUS = NOT POSDEF’ and ERR MATRIX NOT POS-DEF’

Is that okay to change maximum function call in this case?

And I think NOT POSDEF means ‘not positive definite’.
(well it is curve fit)
Then is that possible to some parameters are correlated?
(Maybe I should fix some parameters…)

Thank you and have a nice day! :smiley:

-J.E.Suh

HI,

If you git call limit it is good you increase the maximum.
Not posdef refers to the Hessian matrix, that is not positive defined. That could also mean that you are not in a region where your minimisation function is not a convex function in that region. This is not good if you are at the minimum.
It could also due to some parameters which are 100% correlated. So fixing parameters in this case can help.

Bets Regards

Lorenzo