gnuplot: how to put two figures side by side - gnuplot

Question

I'm trying to put two figures side by side using gnuplot with multiplot.
I want the resulting image to be rectangular so I use set size 2, 1. I also set the set multiplot layout 1, 2 option. However, the resulting image only uses the left part of the available space. Any help will be appreciated.
Thanks
Ahmet
Here is the resulting image
http://tinypic.com/r/33mlz04/6
And below is the gnuplot commands I'm using.
set terminal postscript eps color enhanced
set output 'figure.eps';
set size 2,1;
set multiplot layout 1, 2 ;
set title "Figure 1";
plot "data1.txt"
set title "Figure 1";
plot "data2.txt"
unset multiplot
Although I'm not very sure, with some trial and error I have solved it
set terminal postscript eps color enhanced
set output 'eps/image.eps';
set size 1,0.5;
set multiplot layout 1, 2 ;
set title "Figure 1";
set size 0.5,0.5;
plot "data/data1.txt"
set title "Figure 1";
set size 0.5,0.5;
plot "data/data2.txt"
unset multiplot

Answer 1

Try something like:
set terminal postscript eps color enhanced size 10,5
set output 'figure.eps';
set multiplot layout 1, 2 ;
set title "Figure 1";
plot "data1.txt"
set title "Figure 1";
plot "data2.txt"
unset multiplot
When you set the size on the terminal specification line, that determines the actual size of the plot canvas (in inches in this case). When you use set size on a separate line, that sets the size of the plot in relative units of the canvas size. This is different in older versions of gnuplot. For perhaps a better explanation, try help set size in gnuplot.

Answer 2

For even more control over the size/position of the plot, you can use set origin in conjuction with set size to change the placement and size of each plot. Finally, the most control can be achieved with set lmargin at <place> (and set rmargin ...) and so-on for tmargin and bmargin where the "lrtb" stand for left, right, top and bottom respectively.
So, to get a plot to fill all of the available space (left to right), you could:
set multiplot
set lmargin at 0
set rmargin at .5
plot sin(x)
set lmargin at .5
set rmargin at 1
plot cos(x)
unset multiplot
However, this is (usually) overkill. Usually gnuplot tries to make the margins big enough for your labels and such, but setting the margin explicitly disables that. I would suggest you go with the solution by andyras.

Answer 3

if you are having problems using this method for more than 2 figures add 'set origin 0,0' after 'set size 0.5,0.5'.
For example, for three figures :
set terminal postscript eps color enhanced
set output 'eps/image.eps';
set size 1.5,0.5;
set multiplot layout 1, 3 ;
set title "Figure 1";
set size 0.5,0.5;
set origin 0,0
plot "data/data1.txt"
set title "Figure 2";
set size 0.5,0.5;
set origin 0,0
plot "data/data3.txt"
set title "Figure 3";
set size 0.5,0.5;
set origin 0,0
plot "data/data3.txt"
unset multiplot