[Tex/LaTex] The equation number doesn’t appear

equations

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}:

\documentclass[11pt,a4paper,twoside,openright]{report}

\usepackage{amsmath,amssymb}            

\usepackage[USenglish]{babel}
\usepackage[latin1]{inputenc}

\pagestyle{empty}

\begin{document}

\begin{equation}
\label{10}
  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{equation}

And here is a reference to the equation \eqref{10}

\end{document}

output of example code

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"

{\footnotesize
 ...
}

you will get this result:

output of enhanced wxample code

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.

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