RE: Problem with the nonlinear fitting procedure in Origin 4.1.I have seen the problem you describe regarding the strange numbers appearing in the box which specifies the Max Number of Iterations. These strange numbers only appear in the 32bit version. Valid selections within this drop down list are the choices ranging from 2 to 200. The numbers listed beyond this are not valid. If a number between 2 and 200 is chosen, there is not a problem with the fitting iterations. This problem has been reported to the developers and will be fixed for next release.
I have not been able to reproduce the problem you describe regarding the exponential decay fit. I fit some sample data in both version 4.0 and 4.1. Both results were exactly the same. Could you please email detailed steps regarding this problem to the Microcal Technical Support department at tech@microcal.com