<div>On 2/24/07, Andrew Price <<a href="mailto:andy@andrewprice.me.uk">andy@andrewprice.me.uk</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> On 24/02/07 17:54, Robin Menneer wrote: > I have a problem with fitting a curve to some data and would like help > please.  The data are: > x=375, 375, 375, 355, 315, 268,195, 110, 0 > y=2500, 2150, 1920, 1600, 1250, 936, 624, 312, 0 > I need a program that will draw a line of best fit (for me to print) > according to different parameters,, especially log and power and find the > best for me, and give me the equation for it. gnuplot seems like a good tool for this job. It's a tool with a wide range of options and commands so it can seem a bit daunting to use it for the first time (I should know, I used it for the first time today :)) Anyway, here's an example of how to do it (I'm assuming you've already installed the gnuplot package): Put your X and Y data in a text file in columns like: 375    2500 375    2150 375    1920 355    1600 315    1250 268    936 195    624 110    312 0      0 Then open a terminal and go to the directory with the data file in it and run gnuplot: $ cd /path/tomy/datafile/dir/ $ gnuplot Once you're in the gnuplot "shell", tell it to plot columns 1 and 2 as x and y respectively, giving the curve a title: gnuplot> plot "mydatafile.dat" using 1:2 title 'Data' smooth csplines Removing "smooth csplines" would make gnuplot plot each individual point without a curve, replacing "csplines" with "unique" joins the dots. A whole range more options can be found in the documentation [1]. If you want to plot the data to an image file, precede the plot command with something like these two commands: gnuplot> set terminal png gnuplot> set output 'mygraph.png' For a list of other output file types, just type 'set terminal' without an option. (Don't let the command line nature of this daunt you, it's pretty simple and tutorials like [2] and demos like [3] show you how powerful it can be) [1] <a href="http://www.gnuplot.info/docs/gnuplot.html"> http://www.gnuplot.info/docs/gnuplot.html</a> [2] <a href="http://www.duke.edu/~hpgavin/gnuplot.html">http://www.duke.edu/~hpgavin/gnuplot.html</a> [3] <a href="http://www.gnuplot.info/demo/simple.html">http://www.gnuplot.info/demo/simple.html </a> Hope this helps. -- Andy Price IRC: welshbyte <a href="http://andrewprice.me.uk">http://andrewprice.me.uk</a></blockquote><div> Thanks - it does look daunting and I'll need a quiet afternoon  (or day ?)  to puzzle my way through it.  Many Thanks Robin </div> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">-- <a href="mailto:ubuntu-uk@lists.ubuntu.com">ubuntu-uk@lists.ubuntu.com </a> <a href="https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk">https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk</a> <a href="https://wiki.kubuntu.org/UKTeam/">https://wiki.kubuntu.org/UKTeam/</a> </blockquote> </div>