Reading dataset value into a gnuplot variable (start of X series)

Question

I originally thought this may be the same as gnuplot - start of X series - Stack Overflow - but I think this is slightly more specific.

Since I\'m interested in fin

Answer 1

Hmmm... OK, I got something:

initer(x) = (!exists("first")) ? first = x : first ;
plot "inline.dat" using ($1-initer($1)):2 with impulses linewidth 2

... but this looks more like "capturing" a variable, than reading it (as the function initer is being used to scan a stream of numbers, detect the first one, and return its value) :) Hope there is a better way of doing this ....