[ubuntu-uk] Curve-fitting program or package (a gnuplot example)

Robert McWilliam rmcw at allmail.net
Sat Mar 3 19:45:28 GMT 2007

On Sat, 3 Mar 2007 15:25:28 +0000
"Robin Menneer" <robinmenneer at gmail.com> wrote:
> Postscript.  Found (eventually) at www.xru.org.index.asp a program
> which I used on line (on a mac), is very simple, and apart from not
> drawing the graph, did all I wanted, including giving me the points
> for me to draw.  It should be part of the Ubuntu package.

I've just discovered that oocalc may in fact do what you want, or at
least a bit closer to it than I thought, if you select XY plot instead
of line graph for the plot type (the next step lets you select between
points or lines etc.) I've put a screenshot showing the icon for XY plot
online at http://ormiret.com/foo/x-y.png
since oocalc doesn't seem to display the name until after you click on
the icon.

This just draws straight lines between the points rather than higher
order interpolation so if you don't have many points you might have to
implement some form of interpolation in the spread sheet (I can't find
any interpolation formulae in oocalc).

I think this is proving complicated because although you have what
seems like a fairly simple plotting problem it is quite rare for
someone to want this without wanting to do other data processing steps
and so using something like octave[1], or the numeric libraries for
their programming language of choice[2]. You've unfortunately got a
problem that lies just beyond what is easy with oocalc (unless joining
the dots is sufficient). 

[1] http://www.gnu.org/software/octave/
[2] e.g. http://scipy.org/ for python

Robert McWilliam     rmcw at allmail.net    www.ormiret.com

Instructions should be read first, or not at all.
Anything else is admitting defeat...

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