List of possible improvements:
A. contraints on parameter - DONE
* https://lmfit.github.io/lmfit-py/bounds.html
* https://root.cern.ch/doc/master/classTMinuit.html
* http://stackoverflow.com/questions/11312004/python-parameter-transformation-according-to-minuit
B. support fix parameter - DONE
* https://sourceware.org/ml/gsl-discuss/2002-q2/msg00208.html
* https://lists.gnu.org/archive/html/help-gsl/2005-04/msg00013.html
* http://www.physics.brocku.ca/~tharroun/gsl_fit/group__lstsq.html
C. use resulting parameter as new start values (optional) - DONE
D. evaluate full range/selected range of fitted function - DONE
E. Option to ignore errors when fitting. - DONE
F. Find fit parameter in user supplied fit function automatically - DONE
* Currently the fit parameter has to be given by the user which is more work than necessary. We should check if we can get this information from the parser.
G. Improve output of results. - DONE
* use tables to improve visibility - DONE
* calculate t, p- value and conf. interval of parameter - DONE
* calculate p value for chi-square test - DONE
* calculate p value for F test - DONE
* https://reference.wolfram.com/language/howto/FitModelsWithMeasurementErrors.html
* https://de.wikipedia.org/wiki/Einstichproben-t-Test
* http://reliawiki.org/index.php/Multiple_Linear_Regression_Analysis#Estimating_Regression_Models_Using_Least_Squares
* https://onlinecourses.science.psu.edu/stat501/node/297
* http://reliawiki.org/index.php/Simple_Linear_Regression_Analysis
* https://onlinecourses.science.psu.edu/stat501/node/295
H. support different weighting types - DONE
* http://www.originlab.de/doc/Origin-Help/FIt-with-Err-Weight
* http://reference.wolfram.com/language/ref/Weights.html
* http://www.graphpad.com/guides/prism/6/curve-fitting/index.htm?reg_weighted_nonlinear_regression.htm
I. support x-errors for fitting - DONE
* http://wwwhep.physik.uni-freiburg.de/fp/origin/Kap4.pdf
* http://stackoverflow.com/questions/22670057/linear-fitting-in-python-with-uncertainty-in-both-x-and-y-coordinates
* http://stackoverflow.com/questions/12918968/gnuplot-fitting-with-error-variable-in-x-and-y
* https://www.mpp.mpg.de/~caldwell/ss05/Lecture11.pdf
* http://originlab.com/doc/Origin-Help/LinearFit-XErr-Dialog
* http://www.originlab.com/doc/Origin-Help/Ref-Linear-XErr
* https://stats.stackexchange.com/questions/222335/line-of-best-fit-for-data-with-error-in-x-and-y
* http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422013000600025
J. Implement missing fit models for statistical distributions - DONE
K. Add button to create a label with fit results. - TODO
L. support asymmetric errors when fitting. - DIFFICULT
errors are currently taken into account by symmetric weights. How can we support asymmetric errors?
M. Guess initial parameters (see Origin parameter initializing) - EVALUATE
Can only be done for simple fit models. To get good initial values a fit should be done :-)
N. Shared parameter of multiple data sets (ensemble averaging (?), see Origin) - POSTPONED
Fitting multiple data sets is not supported yet