5.8 fit

fit [<range specifier> ...] <function> '<datafile>'
    [index <index specifier>] [using <using specifier>]
    via <variable>[, <variable>, ...]

The fit command may be used to fit functional forms to data points in datafiles. A simple example might be:

f(x) = a*x+b
fit f(x) 'datafile' index 1 using 2:3 via a,b

The coefficients to be varied are listed after the keyword ‘via’; the keywords ‘index’, ‘every’ and ‘using’ have the same meanings as in the plot command.

This is useful for producing best-fit lines and also has applications for estimating the gradients of datasets. The syntax is essentially identical to the used by gnuplot, though a few points are worth noting, which are outlined in Section 2.9.