Thru

The thru function is provided for backward compatibility.

Syntax:

        plot 'file' thru f(x)

It is equivalent to plot 'file' using 1:(f($2)). While the latter appears more complex, it is much more flexible.

The more natural

  plot 'file' thru f(y)

also works (i.e. you can use y as the dummy variable).

thru is parsed for splot and fit but has no effect.