#This file was created by <larsbj> Sun Dec  5 17:46:35 1999
#LyX 1.0 (C) 1995-1999 Matthias Ettrich and the LyX Team
\lyxformat 2.15
\textclass article
\language english
\inputencoding latin1
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\paperfontsize 10
\spacing single 
\papersize letterpaper
\paperpackage a4
\use_geometry 0
\use_amsmath 0
\paperorientation portrait
\secnumdepth 3
\tocdepth 3
\paragraph_separation indent
\defskip medskip
\quotes_language english
\quotes_times 2
\papercolumns 0
\papersides 1
\paperpagestyle plain

\layout Title

Numbering and Labeling equations
\layout Author

Alejandro Aguilar-Sierra
\layout Standard

A simple equation can be numbered by two ways.
 The first is invocating the LyX command 
\family typewriter 
math-number
\family default 
.
 The corresponding number
\begin_float footnote 
\layout Standard

Or a 
\series bold 
#
\series default 
 mark since true numbering is not yet implemented.
\end_float 
 will appear after the right end of the equation.
 
\layout Standard


\begin_inset Formula 
\begin{equation}
x=y^{2}-3
\end{equation}

\end_inset 


\layout Standard

Usually the equation number will be referred to in the document.
 It's safer to assign a label to the equation, instead of using a fixed
 number.
 Assigning a label to a non-numbered equation will make it numbered automaticall
y.
 With the label 
\series bold 
planck 
\series default 
we can be refer to the equation (
\begin_inset LatexCommand \ref{planck}

\end_inset 

).
\layout Standard


\begin_inset Formula 
\begin{equation}
\label{planck}
E=hv
\end{equation}

\end_inset 


\layout Standard

In the case of an equation array, every line is sequentially numbered.
 It's possible to suppress the number for a single line with the command
 
\family typewriter 
math-nonumber
\family default 
.
 The cursor must be at the row you want not to be numbered.
\layout Standard


\begin_inset Formula 
\begin{eqnarray}
(x+y)(x-y) & = & x^{2}-xy+xy-y^{2}\nonumber \\
 & = & x^{2}-y^{2}
\end{eqnarray}

\end_inset 


\layout Standard

It's possible to label more than one line.
 From the following array of equations we can refer to the equations (
\begin_inset LatexCommand \ref{eq:gs1}

\end_inset 

) and (
\begin_inset LatexCommand \ref{eq:gs2}

\end_inset 

) using their corresponding labels.
\layout Standard


\begin_inset Formula 
\begin{eqnarray}
v_{k+1} & = & w_{k}+b_{1}\label{eq:gs1} \\
w_{k+1} & = & v_{k+1}+b_{2}
\end{eqnarray}

\end_inset 


\layout Standard

To see the final result please preview or print this document.
\the_end