The chi-squared value during the optimization process

[Chaoyue-cpu]

Hello. Thank you for your outstanding work. I've found that there is occasionally an issue where the chi-squared value is too large during operation. Is this normal? Especially when the program just starts: chi2: (before) inf -> (after) 1.16263e-27. After I added other constraints, it even occurs that chi2: (before) nan -> (after) nan.

[Chaoyue-cpu]

I have identified the cause of the NaN issue—the information matrix was set incorrectly. However, the problem of the initial chi-square value being too large still persists.