MATLAB: MATLAB 2020b vs earlier versions

fsolveMATLAB

Dear All,
I am attaching two MATLAB codes to this message, and when I run "Version 15" it produces for "eta" result equal to about 0.08 in MATLAB2020b. But in earlier versions of MATLAB the result is about 0.13.
I was wondering why the difference and if there is any possible problem with the most recent MATLAB release.
Thank you for your help in advance. I am attaching the two codes to this message.

Best Answer

The version with about 0.13 is not an especially good fit; it has a sum-of-squared-errors of about 0.06 for the fsolve.
You can do better near 0.08. In particular, the following x has a SSE of about 1E-16 for the fsolve:
2.41822013449192763, 0.393312505963807846, 0.463898429336224605, 1.00253486482090381, 0.345768760645462359, 0.290239202125991747, 1.37204767772094183, 0.0843373491237134065, 0.927918117994239955