GNUPlot Manual

36 SET-SHOW gnuplot 4.0 127
Several possibly useful files about gnuplot’s PostScript are included in the /docs/psdoc subdirectory of
the gnuplot distribution and at the distribution sites. These are "ps symbols.gpi" (a gnuplot command
file that, when executed, creates the file "ps symbols.ps" which shows all the symbols available through
the postscript terminal), "ps guide.ps" (a PostScript file that contains a summary of the enhanced
syntax and a page showing what the octal codes produce with text and symbol fonts), "ps file.doc" (a
text file that contains a discussion of the organization of a PostScript file written by gnuplot), and
"ps fontfile doc.tex" (a LaTeX file which contains a short documentation concerning the encapsulation
of LaTeX fonts with a glyph table of the math fonts).
A PostScript file is editable, so once gnuplot has created one, you are free to modify it to your heart’s
desire. See the editing postscript (p. 128) section for some hints.
36.59.55.1 Enhanced postscript Several terminal types support an enhanced text mode in which
additional formatting information is embedded in the text string.
Enhanced Text Control Codes
Control Examples Explanation
^ a^x superscript
_ a_x subscript
@ @x or a@^b_c phantom box (occupies no width)
& &{space} inserts space of specified length
~ ~a{.8-} overprints ’-’ on ’a’, raised by .8
times the current fontsize
Braces can be used to place multiple-character text where a single character is expected (e.g., 2^{10}).
To change the font and/or size, use the full form: {/[fontname][=fontsize | *fontscale] text}. Thus
{/Symbol=20 G} is a 20-point GAMMA and {/*0.75 K} is a K at three-quarters of whatever fontsize
is currently in effect. (The ’/’ character MUST be the first character after the ’{’.)
If the encoding vector has been changed by set encoding, the default encoding vector can be used
instead by following the slash with a dash. This is unnecessary if you use the Symbol font, however —
since /Symbol uses its own encoding vector, gnuplot will not apply any other encoding vector to it.
The phantom box is useful for a@^b c to align superscripts and subscripts but does not work well for
overwriting an accent on a letter. (To do the latter, it is much better to use ’set encoding iso 8859 1’
to change to the ISO Latin-1 encoding vector, which contains a large variety of letters with accents or
other diacritical marks.) Since the box is non-spacing, it is sensible to put the shorter of the subscript
or superscript in the box (that is, after the @).
Space equal in length to a string can be inserted using the ’&’ character. Thus
’abc&{def}ghi’
would produce
’abc
ghi’.
The ’˜ ’ character causes the next character or bracketed text to be overprinted by the following character
or bracketed text. The second text will be horizontally centered on the first. Thus ’˜ a/’ will result in
an ’a’ with a slash through it. You can also shift the second text vertically by preceding the second text
with a number, which will define the fraction of the current fontsize by which the text will be raised or
lowered. In this case the number and text must be enclosed in brackets because more than one character
is necessary. If the overprinted text begins with a number, put a space between the vertical offset and
the text (’˜ {abc}{.5 000}’); otherwise no space is needed (’˜ {abc}{.5 — }’). You can change the font
for one or both strings (’˜ a{.5 /*.2 o}’ — an ’a’ with a one-fifth-size ’o’ on top — and the space between
the number and the slash is necessary), but you can’t change it after the beginning of the string. Neither
can you use any other special syntax within either string. You can, of course, use control characters by
escaping them (see below), such as ’˜ a{\^}’
You can access special symbols numerically by specifying \character-code (in octal), e.g., {/Symbol
\245} is the symbol for infinity.