gnuplot

Some notes about gnuplot.
This is a nice tool. I am also thinking about getting a matlab which never expires.
The drawing ability of matlab is amazing.

Generally, we want to find a tool that could load the input data file, store the customization of the user, and generate portable figure file format.
In this case, we can write the scripts to draw the graphs and finish this job automatically.

Let's look at gnuplot to see how it fits the needs.

One basic example illustrating the configuration is like this:
set terminal latex
set output "eg3.tex"
set format xy "$%g$" #set the data format in the figure
set title "This is another plot" #title
set xlabel "$x$ axis" #x and y label
set ylabel "$y$ axis"
set key at 15,-10
plot x with lines, "eg3.dat" with linespoints

If we want to print the data in log scale, then the command should be
set log xy #in log scale, the y range must be greater than 0

use:
set xrange [ : ] to set the range of x, similarly for y set yrange..

2. How to load the data from files
The data file can be

Discrete data contained in a file can be displayed by specifying the name of the data file (enclosed in quotes) on the plot or splot command line. Data files should have the data arranged in columns of numbers. Columns should be separated by white space (tabs or spaces) only, (no commas). Lines beginning with a # character are treated as comments and are ignored by Gnuplot. A blank line in the data file results in a break in the line connecting data points.

For example your data file, force.dat , might look like:

      # This file is called   force.dat
     # Force-Deflection data for a beam and a bar
     # Deflection    Col-Force       Beam-Force
     0.000              0              0   
     0.001            104             51
     0.002            202            101
     0.003            298            148
     0.0031           290            149
     0.004            289            201
     0.0041           291            209
     0.005            310            250
     0.010            311            260
     0.020            280            240

You can display your data by typing:

      gnuplot>  plot  "force.dat" using 1:2 title 'Column', \
                     "force.dat" using 1:3 title 'Beam'