8.11 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 in files. A simple example might be:

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

The coefficients to be varied are listed after the via keyword; the modifiers 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 in estimating the gradients of datasets. The syntax is essentially identical to that used by Gnuplot, though a few points, outlined in Section 2.11, are worth noting.