The set size command scales the displayed size of the plot.
Syntax:
set size {{no}square | ratio <r> | noratio} {<xscale>,<yscale>}
show size
The <xscale> and <yscale> values are the scaling factors for the size of the plot, which includes the graph and the margins.
ratio causes gnuplot to try to create a graph with an aspect ratio of <r> (the ratio of the y-axis length to the x-axis length) within the portion of the plot specified by <xscale> and <yscale>.
The meaning of a negative value for <r> is different. If <r>=-1, gnuplot tries to set the scales so that the unit has the same length on both the x and y axes (suitable for geographical data, for instance). If <r>=-2, the unit on y has twice the length of the unit on x, and so on.
The success of gnuplot in producing the requested aspect ratio depends on the terminal selected. The graph area will be the largest rectangle of aspect ratio <r> that will fit into the specified portion of the output (leaving adequate margins, of course).
square is a synonym for ratio 1.
Both noratio and nosquare return the graph to the default aspect ratio of the terminal, but do not return <xscale> or <yscale> to their default values (1.0).
ratio and square have no effect on 3-d plots.
set size is relative to the default size, which differs from terminal to terminal. Since gnuplot fills as much of the available plotting area as possible by default, it is safer to use set size to decrease the size of a plot than to increase it. See set terminal for the default sizes.
On some terminals, changing the size of the plot will result in text being misplaced.
Examples:
To set the size to normal size use:
set size 1,1
To make the graph half size and square use:
set size square 0.5,0.5
To make the graph twice as high as wide use:
set size ratio 2