The design of the A-R ligature

with Computer Modern, Times, and Palatino

Agostino De Marco
January 30, 2012

version 2.0

Abstract
The aspect ratio symbol is used very much in aerodynamics and aeronautics to express
a particular geometric property of airplane wing planforms. Very often in textbooks the
quantity is simply called A because of typographic limitations of the typesetting system. In
1998 Claudio Beccari (CB) came up with a well designed glyph, particularly suited for use
with Computer Modern fonts and its siblings. An example of use of this symbol is given by
the following definition of the aspect ratio of a wing:
span)
b
A = (wing(wing
=
planform area)
S
2

As it can be seen from the above formula, the glyph is a ligature between a capital A and
a capital R, much as the \AE command produces the ligature between a capital A and a
capital E.

Package usage

The symbol
is accessed in LATEX by means of the package ar and is produced by the command
\AR, in both math and text modes.
The package is loaded by the usual command:
\usepackage[options]{ar}
The available options are the following:
CM is the default setting and produces glyphs that are consistent with Computer Modern, CMsuper, EC, and Latin Modern fonts;
TM or TX selects glyphs that are suitable with the Times, and Times eXtended fonts, but they
are generally suited with other narrow fonts as, for example, the Linux Libertine ones.
PA or PX selects glyphs that are suitable with Palatino, Palatino eXtended, Mathpazo, and other
wide fonts.
These options have been defined to allow the consistent use of the aspect ratio symbol in
documents typeset with fonts other than Computer Modern and its siblings. Hopefully additional
options will be roved in the future for a more comprehensive font support.

Package contents

The package contains several files of different types:

 The METAFONT source files arsize.mf in order to produce the bitmapped fonts, in case
the user wanted to typeset a document in DVI format and wanted to preview it with a DVI
viewer. The size ranges from 5 to 12, in the usual sequence as any other math font in the
TEX system.
The METAFONT source files for sans serif medium and bold fonts in 10pt size and the only
source file for the typewriter monospaced version of the font in 10 pt size.
The metric files *.tfm for both the bitmapped and vector fonts.
The vector font files for the Computer Modern version, arseriessize.pfb includiong the
single 10pt size sans serif and typewriter style fonts, and the vector font files for the Times
and Palatino variants, amarseriesi.pfb and aparseriesi.pfb. The metaseries is either
empty or equal to b, for medium and bold series respectively.
The ar.sty extension file through which the suitable settings are made and the
made available to the user.

A symbol

The aspectratio.map file necessary to configure your system for having the vector typesetting engines access the vector fonts.

Installing the package and the fonts

If the whole package is not already installed by your TEX system distribution, we suggest to create
an AspectRatio folder under these branches of your personal (for individual usage) or local (for
machine wide usage) TEXMF tree1 :
.../doc/latex/AspectRatio/: move this filear.pdf file to this folder;
.../source/latex/AspectRatio/: move the corresponding ar.tex file to this folder;
.../tex/latex/AspectRatio/: move the ar.sty to this folder;
.../fonts/source/public/AspectRatio/: move all the *.mf files to this folder;
.../fonts/tfm/public/AspectRatio/: move all the *.tfm files to this folder;
.../fonts/type1/public/AspectRatio/: move all the *.,pub files to this folder;
.../fonts/map/AspectRatio/: move all the *.map files to this folder.
If your TeX distribution requires it, refresh the file name database according to the procedure
described in your system guide.
In order to use the Type 1 fonts, you must follow the instructions that came with your TEX
system distribution; the idea with all distributions is to let the configuration file updmap.cfg know
about the new map file; you have to execute a TEX system command in order to regenerate the
map file suitable for the pdftex, dvips, and dvipdfm programs; after the operation is completed
the LATEX engine will use the bitmapped fonts in the DVI output file, while the other vector font
oriented engines will use the vector fonts in Type 1 format.

Author guide

The symbol , as a means for indicating the aspect ratio, is meaningful only in mathematics, so
that only the italic shape makes sense. As an isolated symbol the
ligature might be used also
in text mode outside a math expression.
Keeping in mind that only the italic shape is available, with the Computer Modern and the
Times or Palatino variants, the ligature produced by \AR is sensitive to the text series declarations
or commands. In math mode the bold symbol is available only through the explicit command \ARb.

1 Here we use the UNIX folder separator /; change / with \ on Windows platforms. Moreover we do not specify
the full path from the disk root, but we show only the end branches preceded by an ellipsis.

Table 1: Symbols and commands in both math and text modes

Math
symbol

AA

Medium ligature
Bold ligature
Medium sans serif ligature
Bold sans serif ligature
Monospaced ligature

Math
command

Text
symbol

\AR
\ARb

AAA
A
A

Text
command
\AR
\textbf{\AR}
\ARss
\textbf{\ARss}
\ARtt

By means of the specified options it is possible to get the corresponding glyphs in Times or Palatino. Remember,
though, that both Times and Palatino have only the proportional serifed medium and bold fonts, so there is no
possibility of using the sans serif or the monospaced version. Avoid using the Computer Modern monospaced version;
it is available, but certainly the complex ligature does not fit well into the narrow character width of the monospaced
fonts.

This asymmetry arises in order to avoid defining yet another math font group with an alphabet for
medium math and a variant for bold math. Remember that when typesetting math, the various
typesetting engines can handle a maximum of 16 alphabets; it does not happen very often, but
while testing this very package with different fonts we eventually exceeded this maxim number
and we produced an immediate fatal error. Therefore we decided that for just one glyph it was
totally useless to define a new math group and we went around this problem with a \mathcoice
work-around that allows us to actually typeset in the proper math size within a box to be used in
math mode; apparently complicated, but actually very simple. This, on the other side, forbids us
to use the regular math font switching commands to adapt the font family to the requested one.
Table 1 shows the various ways to produce the
symbol in math and in text mode with
the various families available with the Computer Modern compliant
symbol. With Times and
Palatino there is only one family available, the serifed one, and the variant commands resort to
the italic shape.
If you get the source file of this documentation (ar.tex and comment out certain lines in the
preamble, while uncommenting certain other lines (clearly marked in the preamble itself) you can
typeset again this same file with the Times o Palatino fonts and you can verify the outcome of the
various commands in the above mentioned table and in the following examples.
Here we show the various series, shapes, and sizes available with the package; with the CM
fonts and their siblings you get the various families produce the proper variations; with the Times
and Platino variants you get only the italics medium and bold variations always in serifed italics.

(CM Regular)
(CM Bold)
(CM Sans serif regular)
(CM Sans serif bold)
(CM Monospaced regular)

A
A
A
A
A
A
A
AAAAAAAA

AAA
AAAAAAA
AAAAAAAA
AAAAA

AA

AAA

AAA

Legal issues

This work is distributed under the LaTeX Project Public Licence, version 1.3 or later; the Licence
text is distributed with any distribution of the TEX system.
This package is temporarily maintained by Claudio Beccari claudio dot beccari at gmail
dot com.