+To be able to use xymatrices, the LaTeX-package
+\series bold
+xypic
+\series default
+ must be installed.
+ A xymatrix is created by inserting the command
+\series bold
+
+\backslash
+xymatrix
+\series default
+ in a formula.
+ Then you are able to add new matrix columns and rows like for normal matrices,
+ see
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "sec:Matrices"
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Standard
+In contrary to amscd diagrams, xymatrices supports diagonal and curved arrows,
+ and much more.
+ All possibilities to create commutative diagrams and decorations are explained
+ in detail in the
+\emph on
+XY-pic manual
+\emph default
+ that you find in the menu
+\family sans
+Help\SpecialChar \menuseparator
+Specific
+\begin_inset space ~
+\end_inset
+
+Manuals
+\family default
+.
+\end_layout
+
+\begin_layout Subsection
+
+\noun on
+Feynman
+\noun default
+ Diagrams
+\begin_inset Index idx
+status collapsed
+
+\begin_layout Plain Layout
+Diagrams ! Feynman
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+To be able to use
+\noun on
+Feynman
+\noun default
+-diagrams, the LaTeX-package
+\series bold
+feyn
+\series default
+ must be installed.
+ A
+\noun on
+Feynman
+\noun default
+-diagram is created by inserting the command
+\series bold
+
+\backslash
+Diagram
+\series default
+ in a formula.
+ Then you are able to add new matrix columns and rows like for normal matrices,
+ see
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "sec:Matrices"
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Standard
+Examples how to create
+\noun on
+Feynman-
+\noun default
+diagrams in LyX is given in the
+\emph on
+Feynman-diagram manual
+\emph default
+ that you find in the menu
+\family sans
+Help\SpecialChar \menuseparator
+Specific
+\begin_inset space ~
+\end_inset
+
+Manuals
+\family default
+.
+\end_layout
+
+\begin_layout Section
+User-defined Commands
+\begin_inset Index idx
+status collapsed
+
+\begin_layout Plain Layout
+User-defined commands
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset Note Greyedout
+status open
+
+\begin_layout Plain Layout
+
+\series bold
+Note:
+\series default
+ The names of user-defined commands and macros may only consist of Latin
+ letters.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
+The Command
+\backslash
+newcommand
+\begin_inset CommandInset label
+LatexCommand label
+name "sub:The-Command-newcommand"
+
+\end_inset
+
+
+\begin_inset Index idx
+status collapsed
+
+\begin_layout Plain Layout
+User-defined commands !
+\backslash
+newcommand
+\end_layout
+
+\end_inset
+
+
+\begin_inset Index idx
+status collapsed
+
+\begin_layout Plain Layout
+Commands ! N !
+\backslash
+newcommand
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Many LaTeX-commands are too long to be used frequently.
+ But it is possible to define with the command
+\series bold
+
+\backslash
+newcommand
+\series default
+ new shorter commands.
+\end_layout
+
+\begin_layout Standard
+The command scheme of
+\series bold
+
+\backslash
+newcommand
+\series default
+ is:
+\end_layout
+
+\begin_layout Standard
+
+\series bold
+
+\backslash
+newcommand{new command name}[number of arguments][optional
+\series default
+
+\series bold
+value]
+\begin_inset Newline newline
+\end_inset
+
+
+\begin_inset Phantom HPhantom
+status open
+
+\begin_layout Plain Layout
+
+\series bold
+
+\backslash
+newcommand
+\end_layout
+
+\end_inset
+
+{command definition}
+\end_layout
+
+\begin_layout Standard
+\begin_inset Note Greyedout
+status open
+
+\begin_layout Plain Layout
+
+\series bold
+Note:
+\series default
+ Assure that the name of the new command is not already used in your document
+ or by LaTeX-packages that you use.
+ When you for example define the command
+\series bold
+
+\backslash
+le
+\series default
+ for
+\series bold
+
+\backslash
+Leftarrow
+\series default
+, you get an error message because
+\series bold
+
+\backslash
+le
+\series default
+ is already defined as command for
+\begin_inset Quotes eld
+\end_inset
+
+
+\begin_inset Formula $\le$
+\end_inset
+
+
+\begin_inset Quotes erd
+\end_inset
+
+.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The number of arguments is an integer in the range 0
+\begin_inset space \thinspace{}
+\end_inset
+
+-
+\begin_inset space \thinspace{}
+\end_inset
+
+9 and specifies how many arguments the new command should have.
+ With the optional value a value for an optional argument can be predefined.
+ When this is done, the
+\emph on
+first
+\emph default
+
+\emph on
+a
+\emph default
+rgument of the new command is automatically an optional one.
+\end_layout
+
+\begin_layout Standard
+Here are some examples:
+\end_layout
+
+\begin_layout Itemize
+To define the command
+\series bold
+
+\backslash
+gr
+\series default
+ for
+\series bold
+
+\backslash
+Longrightarrow
+\series default
+, the LaTeX-preamble line is:
+\begin_inset VSpace medskip
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\series bold
+
+\backslash
+newcommand{
+\backslash
+gr}{
+\backslash
+Longrightarrow}
+\end_layout
+
+\begin_layout Itemize
+To define the command
+\series bold
+
+\backslash
+us
+\series default
+ for
+\series bold
+
+\backslash
+underline
+\series default
+, the argument (that should be underlined) must be taken into account.
+ For this the preamble line is:
+\begin_inset VSpace medskip
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\series bold
+
+\backslash
+newcommand{
+\backslash
+us}[1]{
+\backslash
+underline{#1}}
+\series default
+
+\begin_inset VSpace medskip
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+The character
+\series bold
+#
+\series default
+ acts as argument placeholder, the
+\series bold
+1
+\series default
+ behind it denotes that it is the placeholder for the first argument.
+\end_layout
+
+\begin_layout Itemize
+For
+\series bold
+
+\backslash
+framebox
+\series default
+ one can e.
+\begin_inset space \thinspace{}
+\end_inset
+
+g.
+\begin_inset space \space{}
+\end_inset
+
+define the command
+\series bold
+
+\backslash
+fb
+\series default
+:
+\begin_inset VSpace medskip
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\series bold
+
+\backslash
+newcommand{
+\backslash
+fb}[3]{
+\backslash
+framebox#1#2{$#3$}}
+\series default
+
+\begin_inset VSpace medskip
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+The two Dollar signs creates the extra formula needed for
+\series bold
+
+\backslash
+framebox
+\series default
+, see
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "sub:Boxes-with-Frame"
+
+\end_inset
+
+.
+\end_layout
+
+\begin_layout Itemize
+To create a new command for
+\series bold
+
+\backslash
+fcolorbox
+\series default
+ where the color for the box need not be specified, the argument for the
+ color is defined optional:
+\begin_inset VSpace medskip
+\end_inset
+
+
+\begin_inset Newline newline
+\end_inset
+
+
+\series bold
+
+\backslash
+newcommand{
+\backslash
+cb}[3][white]{
+\backslash
+fcolorbox{#2}{#1}{$#3$}}
+\series default
+
+\begin_inset VSpace medskip
+\end_inset
+
+
+\begin_inset Newline newline