gnuplot-beta

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.

Re: how to make diff-plot?

[Ethan M. <merritt@u.washington.edu>]

On Thursday 09 September 2004 03:33 am, Ole Jacob Hagen wrote:
>
> 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?

Not purley from inside gnuplot itself, no.
You would have to constuct a filter operation to apply
to the input file.  You could even do it in-line, though the
command is a bit obscure.  Something like

plot '< echo " " | cat - data.dat | paste - data.dat' \
     using 1:($2-$5)

You'd have to tweak this to handle the first and last
lines in some fashion.