[OS X TeX] Effect of `leqno' on \begin{gather} and \begin{align}

[Don Green Dragon]

Hi All,

I typeset with LaTeX and am using TeXShop 2.38 running under Mac OS X 10.6.7.

My normal document class line is:

\documentclass [11pt, fleqn, leqno] {book}

and it is followed by

\usepackage{amsmath}

plus a horde of other packages and used-defined stuff. But the above two lines appear to be the crux of what I am concerned with. 

When I use math environments which number equations, then the typesetting of \begin{gather} and \begin{align} is not what I expect and does not correspond to what I find in George Graetzer's book, and  Graetzer does give examples where equations are numbered at the left margin.

The problem is this:

If the source code is:

\documentclass [11pt, fleqn, leqno] {book}
\usepackage{amsmath}
\begin{document}
\mainmatter
The equations are:
\begin{gather}
a = b+c\\
x = y+z
\end{gather}
\end{document}

then it typesets as (essentially):

==========
The equations are:

(1) 	a=b+c
(2)	x=y+z
==========

which is fine, but .... NOTE that the above comes before any \chapter command. However, now I include a \chapter command, as in 

\begin{document}
\mainmatter
\chapter[Short Title]{\centering {The Loooong Title for Chapter 1}}
The equations are:
\begin{gather}
a = b+c\\
x = y+z
\end{gather}
\end{document}

and the above typesets as (ignoring the two chapter heading lines):

==========
The equations are:

(1.1) 
	a=b+c
(1.2)
	x=y+z
==========

I was expecting:

==========
The equations are:

(1.1) 	a=b+c
(1.2)	x=y+z
==========

The same sort of phenomenon occurs with \begin{align} and \begin{alignat} and I get the same response on replacing {book} with {memoir}.

I tried other versions of the \documentclass line, such as

\documentclass [11pt, fleqn] {book}

which is okay within a \chapter command except for the fact that the equation numbering is at the right margin which I would like to avoid. Similarly, 

\documentclass [11pt, leqno] {book}

is okay except for the equations being centered.

If I have to live with the format
==========
The equations are:

(1.1) 
	a=b+c
(1.2)
	x=y+z
==========

then that's life with TeX I guess, but I'm wondering if I've missed something!


Don Green Dragon
fergdc at Shaw.ca