Re: [ROOT] Strange error message while fitting.

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Hi,

Your Hessian matrix is not positive definite  !
The inverse is the error matrix .
Perhaps, the parameters you are fitting are very
correlated .

Eddy
--- Sébastien_Gadrat <gadrat@clermont.in2p3.fr> wrote:
> Hi Rooters,
> 
> I get a strange error message when fitting some
> plots. Among information 
> return by Minuit after the completion of the fit, I
> get "ERR MATRIX NOT 
> POS-DEF" ! Can anyone know what does that mean ?
> Here is the output I get :
> 
>  FCN=153.796 FROM MIGRAD    STATUS=CONVERGED      91
> CALLS          92 TOTAL
>                      EDM=2.47125e-08    STRATEGY= 1 
>     ERR MATRIX NOT 
> POS-DEF
>   EXT PARAMETER                APPROXIMATE       
> STEP         FIRST
>   NO.   NAME      VALUE            ERROR         
> SIZE      DERIVATIVE
>    1  const0       5.72969e+03   7.36832e+01  
> 4.07529e-01  -1.22906e-06
>    2  const1      -8.46984e-01   7.65250e-03  
> 3.44875e-06   7.87522e-02
>    3  const3       9.15351e-02   7.21665e-03  
> 1.82483e-05  -4.06709e-02
>    4  slope1       2.19718e+00   6.64370e-03  
> 2.93137e-06  -4.12211e-02
>    5  slope2       2.08281e+00   6.22503e-03  
> 2.84950e-06   4.62693e-02
>    6  slope3       5.18135e-01   1.17508e-02  
> 3.77755e-05   7.06570e-03
> 
> Thanks,
> Regards,
> 
> Sebastien
> 

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