- install LP 2.4 under Windows - create a new spreadsheet and fill 2 columns with row numbers - create a worksheet - create there an xy-plot - add there a xy-curve - use the menu Analysis -> Data fitting in the spreadsheet - use a custom fit function, for example "exp(a*x)" result: the "a" is not recognized as fit variable and does therefore not occur in the parameters list. There I see 2 variables named "c0" and "c1". So one has to add the "a" there manually and delete the "c" parameters. This is time-consuming and annoying. (MagicPlot and Origin recognizes the fit parameters automatically.) However, - use for the parameter "a" as start value "1" and press recalculate result: one gets this: a = 1±nan (nan %) but more severe is that the plot is overlayed with an empty fit. So fitting is just useless because I of course want to see the fit result I the plot.
Finding the fit parameter automatically is not implemented yet. We will care about this. A result like "1±nan (nan %)" usually means that the fit did not converge and the error could not be estimated. Probably the start value was not chosen well. Can you try a better start value? (I checked it and it works for me) Please supply the data if it still doe not work.
> the "a" is not recognized as fit variable This works now in LP 2.5RC2. > - use for the parameter "a" as start value "1" and press recalculate > result: one gets this: a = 1±nan (nan %) This is still the case. It is clear that the fit did not converge and therefore I expect as user an information like: "The fit did not converge. Please use a different start value for the parameter 'a'."
Created attachment 109058 [details] screenshot describing the axes and fit result error Now the behavior of LabPlot is different. Nevertheless the user does not get the info that the fit did not converge and that he should use different start values. Moreover, the fit plot is incorrect, see the axes in the attached screenshot.
resetting bug status
Hi, i uploaded a new package including the latest fixes (also fixing a parser crash on my system) at https://theorie.physik.uni-konstanz.de/gerlach/labplot/labplot-2.5.0rc3-64bit-setup.exe There are two problems in your screenshot. The axes currently do not support values bigger than 1e+15. That's already on our TODO list. The second problem is the missing Unicode support in the fit result. I do not have this problem but i am no Windows expert to help here.
> There are two problems in your screenshot. The axes currently do not support values bigger than 1e+15. In my opinion that is not a bug but that case that the y-axis has the auto fit option and as you can see this uses internally the values: -4.30099e+42 3.11822e+43 for the axis min/max. To fix this, LabPlot should limit the max/min value to -1e+15/1e+15 of whatever is a sensible value. > missing Unicode support in the fit result Yes, this is only in my build and I haven't yet found out why.
I see that you use Qt 5.9.2. Qt 5.9.3 is available.
This bug has had its resolution changed, but accidentally has been left in NEEDSINFO status. I am thus closing this bug and setting the status as RESOLVED to reflect the resolution change.