Re: Unusual Warning Message from Minuit...

Hi,

The message means that MINOS failed, because it could not find the parameter points for which your likelihood or least square function is equal to UP. This could be due to some problem in the function shapes. Your found minimum is probably fine, but the error is probably not really correct, since the likelihood function is not anymore a parabola far away from the minimum. I would try to perform a scan or better do a profile likelihood plot, for the parameter that MINOS gives you the problem.

Best Regards

Lorenzo
On Apr 12, 2011, at 1:32 AM, Pierre-Luc Drouin wrote:

> Hi,
>
> I have been getting unusual warning messages from Minuit from a new type of fit I am attempting. MiGrad runs successfully without any warning, Minos only gives the warning below and then exits with a status of "PROBLEMS", but then it claims the error matrix is accurate. How should I interpret this kind of output exactly?
>
> Thanks!
>
> **********
> ** 7 **MINO
> **********
> MINUIT WARNING IN MNCROS
> ============== Cannot find slope of the right sign
> MINUIT WARNING IN MNCROS
> ============== Cannot find slope of the right sign
> FCN=-26341.7 FROM MINOS STATUS=PROBLEMS 60110 CALLS 67948 TOTAL
> EDM=3.57579e-06 STRATEGY= 0 ERROR MATRIX ACCURATE
>
Received on Tue Apr 12 2011 - 15:05:34 CEST