- not so Frequently Asked Questions -

update 2004/9/5

About Label (No.1)

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I want to use super/subscripts in a text.

The enhanced postscript terminal can display super- / sub-script in the labels or axis names. To use this termianl one needs "enhanced" option:

gnuplot> set terminal postscript enhanced

You can write the supersript as X^2, and the subscript is Y_3. To make several letters super- / sub-script, you need brace like Z_{64}. To use super and subscripts at the same time, try Z@^2_{64}.

The following is an example to make legends with the superscripts. The functions are y=sin**2(x), y=sin**3(x), and y=sqrt(sin(x)).

gnuplot> set terminal postscript eps enhanced
gnuplot> set key spacing 1.3
gnuplot> set xrange [ 0 : pi ]
gnuplot> set yrange [ 0 : 1.5 ]
gnuplot> plot sin(x)**2 ti "sin^2(x)", \
sin(x)**3      ti "sin^3(x)",\
sqrt(sin(x))   ti "sin^{1/2}(x)"

When texts in the legend contain super- / sub-scripts, text lines become very close each other. In the example above, the baseline skip was increased to 30% by set key spacing 1.3 .


I want to use Greek letters in a text.

To use Greek letters in a text, you may try using enhanced postscript terminal just like the case of super- / sub-scripts.

gnuplot> set terminal postscript enhanced

The Greek letters can be displayed by {/Symbol a}. This gives "alpha" which corresponds to "a". The relation of the Symbol and alphabet is as follows.

ALPHABET SYMBOL ALPHABET SYMBOL alphabet symbol alphabet symbol
A Alpha N Nu a alpha n nu
B Beta O Omicron b beta o omicron
C Chi P Pi c chi p pi
D Delta Q Theta d delta q theta
E Epsilon R Rho e epsilon r rho
F Phi S Sigma f phi s sigma
G Gamma T Tau g gamma t tau
H Eta U Upsilon h eta u upsilon
I iota W Omega i iota w omega
K Kappa X Xi k kappa x xi
L Lambda Y Psi l lambda y psi
M Mu Z Zeta m mu z zeta

You can also specify various postscript characters by octal codes, for example, {/243} is a pound (L) mark, {/247} is a section mark. See which comes with gnuplot source distribution in detail.

The next example is to draw the linear function y=Alpha x+ Gamma and two Greek letters with those values in the figure.

gnuplot> set terminal postscript eps enhanced
gnuplot> set xrange [ 0 : 5 ]
gnuplot> set label "{/Symbol a}=0.5, {/Symbol g}=0.2" at 2,0
gnuplot> plot 0.5*x-0.2 ti "y={/Symbol a}x-{/Symbol g}"

How do I adjust an interval between X,Y axes and their labels ?

The interval can be controlled by the ofset options of set {x|y}label command.

gnuplot> set xlabel "x" 0.0,1.0

This moves the X-axis label one letter upward. When you give a positive Y ofset, the X label gets into the graph. While the ofset is negative, distance between the X label and the graph becomes larger. Gnuplot tries to draw a graph as large as possible, so the graph hight becomes larger when the X-axis label moves upward. On the contrary the graph becomes small when the X-axis goes downward.

fig/sample4.3 Y offset = 0
fig/sample4.3c Y offset = +5
fig/sample4.3d Y offset = -5

To adjust the Y-axis label, use set ylabel "Y-AXIS" +n,+m where "+n" and "+m" are the Y-axis ofset options. The following examples are to set the X ofset "+5" and "-5". This affects the width of the graph.

fig/sample4.3 X offset = 0
fig/sample4.3c X offset = +5
fig/sample4.3d X offset = -5