# Fine-tuning a commutative diagram

I am trying to type the following simple commutative diagram in LaTeX. I have the basics, but I need for the V to be centered, and for the arrow under the g to be in the opposite direction.

\begin{tikzpicture}[every node/.style={midway}]
\matrix[column sep={4em,between origins},
row sep={2em}] at (0,0)
{ \node(X)   {$X$}  ; & \node(Y) {$Y$}; \\
\node(V) {$V$};                   \\};
\draw[<-] (V) -- (X) node[anchor=east]  {$h$};
\draw[->] (V) -- (Y) node[anchor=north]  {$g$};
\draw[->] (X)   -- (Y) node[anchor=south] {$f$};
\end{tikzpicture}

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To switch the direction of the arrow, just reverse the order: \draw[->] (Y) -- (V) instead of \draw[->] (V) -- (Y). Also, the V node is centered, so perhaps just increasing the length of the line a bit by adding shorten option as in \draw[->, shorten >=-0.5ex] (Y) -- (V) makes it look more centered. –  Peter Grill Jan 1 '13 at 19:56
have you seen Commutative Diagrams and TikZ and a search for commutative diagrams –  cmhughes Jan 1 '13 at 20:00
@PeterGrill When I compile, I still see the V directly beneath the X,rather than centered and diagonally beneath and to the right of the X, as I would like for it to be. Thanks again. –  Michael Dykes Jan 1 '13 at 20:05
@MichaelDykes: Duhh!!! Sorry about that. Not sure what part of "center" was confusing to me. :-) –  Peter Grill Jan 1 '13 at 20:49

Does this solution with tikz-cd help?

\documentclass{standalone}
\usepackage{tikz-cd}

\begin{document}

\begin{tikzcd}[column sep=small]
X \arrow{rr}{f} \arrow[swap]{dr}{h}& &Y \arrow{dl}{g}\\
& V &
\end{tikzcd}

\end{document}


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Actually, it does as this is exactly what I was looking for. In general, what are the differences between tikz and tikz-cd? I mean when is it better to use the latter rather than the former? Thanks again. –  Michael Dykes Jan 1 '13 at 20:18
I am unexpert, but as I see it, tikz-cd is a tikz-based package to easily type commutative diagrams. As you can see, the syntaxis is as easy as xymatrix. –  c.p. Jan 1 '13 at 20:24
Ok,thank you very much! –  Michael Dykes Jan 1 '13 at 20:28
You're welcome. Here is the manual for more information: ctan.unixbrain.com/graphics/pgf/contrib/tikz-cd/tikz-cd-doc.pdf –  c.p. Jan 1 '13 at 20:33