3.24.21 fit

The fit setting defines where the fit command writes its output. If this option was built into your version of gnuplot, it also controls whether parameter errors from the fit will be written into variables.

Syntax:

      set fit {logfile {"<filename>"}} {{no}errorvariables}
      unset fit
      show fit

The <filename> argument must be enclosed in single or double quotes.

If no filename is given or fit is used the log file is reset to its default value "fit.log" or the value of the environmental variable ‘FIT_LOG‘.

If the given logfile name ends with a / or \, it is interpreted to be a directory name, and the actual filename will be "fit.log" in that directory.

If the ‘errorvariables‘ option is turned on, the error of each fitted parameter computed by fit will be copied to a user-defined variable whose name is formed by appending "_err" to the name of the parameter itself. This is useful mainly to put the parameter and its error onto a plot of the data and the fitted function, for reference, as in:

       set fit errorvariables
       fit f(x) 'datafile' using 1:2 via a, b
       print "error of a is:", a_err
       set label 'a=%6.2f', a, '+/- %6.2f', a_err
       plot 'datafile' using 1:2, f(x)