We currently use a very old version of StatGraphics and unfortunately it doesn't run on x64 systems. So I am looking for open-source software that may do the same thing as a replacement. Namely we run non-linear regression on datatasets that results in coefficients (or parameters) of an equation. Typically there can be up to 11 coefficients and up to 6 independent variables.
We also have the ability to filter the dataset so as to not include certain blocks of data. Plotting is also important so that we can see the scatter of the predicted values.
Lastly since I work with a variety of people with various skills this has to have an easy to use GUI or at least that I can learn and teach others.
I have looked at the list here https://en.wikipedia.org/wiki/List_of_statistical_packages but have come up short. Would appreciate some suggestions. I know there are a number of commercial software packages that do this but hoping to keep it open-source.
Update: I went back and looked at StatGraphics and all along I thought it was a 16-bit program when in fact it's a 32-bit program. The installer itself is the one that doesn't work on x64. So I did an xcopy from my 32-bit machine to the 64-bit machine, copied some DLLs to the SysWOW64 folder, imported the file extension registry entries, and boom I got it to work! That should tide us over for a year or two.