how to make diff-plot?

[Ole J. H. <wat...@ya...>]

Hi.

I have datafile, with 3 columns, where column 1 indicates samplenumber,
while col. 2 and col. 3 is values.
I want to make a diff-plot, but how can I accomplish this?

Let say we have two vectors: x and y.
ydiff will consist of   [x(1),  x(2) - x(1), x(3) - x(2), ...., x(N) -
x(N-1)]


How can I make ydiff in gnuplot? Is it possible?

Cheers,

Ole J.