Infinity symbol output too small

[Dr A K Hannaby]

Tex

In amsmath book, why does the \infty (infinity) symbol display so small in
math mode in comparison to other maths characters , say, x, y or a greek
letter such as \beta (Beta)?

Is there a way of scaling the \infty only?

I would prefer it to be larger rather than bolded.

Keith

[Barbara Beeton]

In amsmath book, why does the \infty (infinity) symbol display so small in
math mode in comparison to other maths characters , say, x, y or a greek
letter such as \beta (Beta)?

the first question to ask is, what fonts
are being used? in the computer modern
fonts, the size of \infty compares favorably
with that of x -- the height is the same,
and it's wider (about the width of m). this
is the traditional size and shape. (a good
reference as to the history of the symbol
and its use is "a history of mathematical
notations", by florian cajori, section 421.)

Is there a way of scaling the \infty only?

again, this depends on what fonts are used.

I would prefer it to be larger rather than bolded.

where can we see an example?
-- bb

[Barbara Beeton]

keith,
(cc'ing the list; someone else may be
able to help more than i can.)

On Mon, 31 Dec 2012, Dr A K Hannaby wrote:

Barbara
I have these entered at the beginning of the "usepackages".

\usepackage{amsmath,bm} % was amsbook,bm
\usepackage{amsfonts} %
\usepackage{appendix} %
\usepackage{palatino} %
\usepackage{bookman} %
\usepackage{helvet} %
\usepackage{amssymb} %
\usepackage{amsthm} %
\usepackage{fix-cm} % metric font size
\usepackage[T1]{fontenc} %

When I reach a line like:
\noindent \fontsize{11.0}{11.0}\selectfont{value will approach
\hspace{2pt}$x^2+3x-7 + a_5+ a_3 + a^2+ a^3\hspace{2pt}-\infty\hspace{2pt}
\beta$},

The infinity seems out of all proportion to the x, y, and beta - even to
the minus sign.
Can you somehow get a "fontsize" command inside the math mode section?

Keith

too many fonts loaded here for me to make a
stab at defining an 11-point math environment;
i've added math at "larger" sizes many times
for headings in ams plain-tex document styles,
and the ams latex document classes "do the
right thing", but they use only cm fonts.

the font size definitions for cm math symbols
are in the file omscmsy.fd in the latex/base
area of tex live; this is called from the
file fontmath.ltx, same area. i think you'll
need something like this to increase the
size of \infty when used with palatino or
bookman, plus the calling mechanism. in
the latex/palatino area there's a file
omsupl.fd but i'm not sure where it's called
from. that info might be a start.
-- bb

-----Original Message-----
From: Barbara Beeton [mailto:***@ams.org]
Sent: 31 December 2012 16:35
To: Dr A K Hannaby
Cc: ***@tug.org
Subject: Re: [texhax] Infinity symbol output too small

In amsmath book, why does the \infty (infinity) symbol display so small
in math mode in comparison to other maths characters , say, x, y or a
greek letter such as \beta (Beta)?

the first question to ask is, what fonts are being used? in the computer
modern fonts, the size of \infty compares favorably with that of x -- the
height is the same, and it's wider (about the width of m). this is the
traditional size and shape. (a good reference as to the history of the
symbol and its use is "a history of mathematical notations", by florian
cajori, section 421.)

Is there a way of scaling the \infty only?

again, this depends on what fonts are used.

I would prefer it to be larger rather than bolded.

where can we see an example?
-- bb

[Heiko Oberdiek]

Post by Dr A K Hannaby
In amsmath book, why does the \infty (infinity) symbol display so small in
math mode in comparison to other maths characters , say, x, y or a greek
letter such as \beta (Beta)?
Is there a way of scaling the \infty only?

It could be scaled using \scalebox of package graphics(/graphicx). The
following example implements a scaled version \Infty that is scaled with
factor \InftyScale. The redefinition takes into account:
* Math styles (via \mathpalette), resizing of the symbol according to
the current math style (subscript, ...)
* The horizontal mathematical axis is kept (by resizing the symbol on
the baseline).
* The short form `^\Infty' can be used (by adding curly braces).

Since the line width is also scaled, the boldness increases by the
same factor using this scaling method.

\documentclass[12pt]{article}
\usepackage{graphicx}

\makeatletter
\newcommand*{\Infty}{%
{\mathpalette\***@aux{}}%
}
\newcommand*{\***@scale}{1.2}% adjust to your needs
\newdimen\***@dim
\newcommand*{\***@aux}[2]{%
\settoheight{\***@dim}{$#1\vcenter{}$}%
\raisebox{\***@dim}{%
\scalebox{\***@scale}{%
\raisebox{-\***@dim}{$\***@th#1\infty$}%
}%
}%
}
\makeatother

\begin{document}
% Testing
\[ a + \infty = \frac{a_\infty}{+\infty^{-\infty}} \]
\tracingmacros=1
\[ a + \Infty = \frac{a_\Infty}{+\Infty^{-\Infty}} \]
\[ - \infty \Infty - \]
\end{document}

Yours sincerely
Heiko Oberdiek