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scikit-hep / iminuit

Jupyter-friendly Python interface for C++ MINUIT2
https://scikit-hep.org/iminuit
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Error: IMinuitWarning: MIGRAD fails to converge #994

Open fgiacchi86 opened 1 month ago

fgiacchi86 commented 1 month ago

Hello guys,

I am using Minuit for a likelihood analysis. It seems that after a value of a parameter "x" the function could degenerate and we expect a sharp decrease in vertical way for the parameter "x=limit_value", but this not happens and the values of "y" remain constant at the value "y(limit_value)=y_limit". Why this happens? The error that I have is "IMinuitWarning: MIGRAD fails to converge for y=###"

You need all script to better understand? Thanks

HDembinski commented 1 month ago

Yes, a minimal script is needed to understand the issue here. Note that parameters which are initially set close to a Minuit limit will probably make Migrad fail to converge, because the transformed objective function that Migrad sees is very distorted then.