What should I do if Fit reaches CALL LIMIT and behaves strangely for some dataset I feed?

_ROOT Version: root_v5.34.36

I’m fitting pion yield w.r.t transverse momentum, but the covariance matrix that I got is identically 0 matrix (7-by-7, for 7 parameters). Then I added the fit option “V”, verbose mode. It tells me call reaches limit:

And right below that, we can see the EXTERNAL ERROR MATRIX is the covariance matrix I wanted, but when I print it again, it still gives me 0-matrix:

So under such circumstance, would it be promising by just increase the limit of the call (how?)? By the way, some other datasets works just fine.

Hi @Shonlin,

I answered in your previous post:

Let me know if this works.

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