I was trying to create an aligned numbering of equations, but I don't know if I am using the right order, the equation numner does not appear:
\documentclass[11pt,a4paper,twoside,openright]{report}
\usepackage{setspace}
\usepackage{graphicx}
\usepackage{tabularx}
\usepackage{tabu}
\usepackage{subfigure}
\usepackage{afterpage}
\usepackage{amsmath,amssymb}
\usepackage{rotating}
\usepackage{fancyhdr}
\usepackage[scriptsize]{caption}
\hyphenation{a-gen-tiz-za-zio-ne}
\usepackage{float}
\usepackage[parfill]{parskip}
\graphicspath{ {images/} }
\usepackage[a4paper,lmargin=2cm,rmargin=2cm]{geometry}
%\setlength{\paperwidth}{16cm}
%\setlength{\paperheight}{24cm}
%\setlength{\oddsidemargin} {2. cm}
%\setlength{\evensidemargin} {2. cm}
%\addtolength{\oddsidemargin} {-0.4 cm}
%\addtolength{\evensidemargin} {-0.4 cm}
%\linespread{1.1}
\usepackage[USenglish]{babel}
\usepackage[latin1]{inputenc}
\renewcommand{\captionfont}{\normalfont \sffamily \itshape \small}
\pagestyle{empty}
\begin{document}
\begin{equation}
\label{10}
\begin{aligned}
\begin{center}
\[
ABD =
\begin{bmatrix}
126102075.631 & 56957543.627 & 0 & 0 & 0 & 0 \\
56957543.627 & 107378189.106 & 0 & 0 & 0 & 0 \\
0 & 0 & 28004682.576 & 0 & 0 & 0 \\
0 & 0 & 0 & 373.068 & 1250.853 & 0 \\
0 & 0 & 0 & 1250.853 & 2.404 & 0 \\
0 & 0 & 0 & 0 & 0 & 1.22
\end{bmatrix}
\]
\end{center}
\end{aligned}
\end{equation}
\end{document}
Best Answer
you're trying too hard. all you need is the single wrapper
\begin{equation}...\end{equation}
:the problem here is that the matrix is too wide for the page, and the equation number is appearing under the right-hand side of the equation, at the normal margin.
if you decrease the font size, wrapping it in this "container"
you will get this result:
as you can see, it is still very wide -- still too wide for the equation number to fit beside it -- but it's more obvious that there is an equation number.
i'm not sure what to suggest to make this fit better; decreasing the type size indefinitely is not an improvement. and the gap between columns is already quite small relative to the contents.