I'm currently trying to fit nonlinear experimental data to find two parameters. Using lsqcurvefit has been working well about 90% of the time, but I wanted to try to improve that. I have found other methods for fitting data, but I'm confused about the differences between them, and how to choose one. I tried using MultiStart in addition to lsqcurvefit, but that did not seem to improve the results. I also tried lsqnonlin without any luck. Do you have any recommendations about other methods/options to try? I have access to the majority of the toolboxes. Some people were discussing the use of robustfit, but I was confused about the implementation of that. Any insight would be greatly appreciated!