Math & Science ⇒ Matrix Column Spacing

[Cham]

I have a 4 x 4 matrix which needs better spacings. Here's a compilable code :

Code: Select all

\documentclass[12pt,letterpaper]{article}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage{amsmath}
\usepackage{tensor}
\newcommand{\qvec}[1]{\boldsymbol{#1}}
\begin{document}
	\begin{equation}
		\frac{d}{d \theta} \!
		\left[ \begin{array}{c}
			\tensor{c}{_1} \\
			\tensor{c}{_2} \\
			\tensor{c}{_3} \\
			\tensor{c}{_4} \\
		\end{array} \right] =
		\left[ \begin{array}{cccc}
			0 & 0 & \tensor{\mathcal{J}}{_{\qvec{F}}} & 0 \\
			1 & 0 & 0 & 2 \tensor{\mathcal{I}}{_{\qvec{F}}} \\
			0 & 0 & 0& \tensor{\mathcal{J}}{_{\qvec{F}}} \\
			0 & 1 & 0 & 0
		\end{array} \right]\!\!
		\left[ \begin{array}{c}
			\tensor{c}{_1} \\
			\tensor{c}{_2} \\
			\tensor{c}{_3} \\
			\tensor{c}{_4} \\
		\end{array} \right]\!\!.
	\end{equation}
\end{document}

Currently, the columns in the 4 x 4 matrix aren't well balanced. How can I tell LaTeX to give the same spacing for each column (without changing the vectors on the left and on the right) ?

Here's a preview :

matrix.jpg (12.92 KiB) Viewed 19496 times

I could use the \phantom command and hack the matrix by hand, but I don't think this would be the correct way to do it.

[Cham]

No idea on this ?

[Stefan Kottwitz]

As you provided a nice compilable example, I gladly suggest a solution. I would use the array package, for defining a centered math column type of a adjustable width:

Code: Select all

\usepackage{array}
\newcolumntype{C}[1]{>{\centering\arraybackslash$}p{#1}<{$}}

In the code, you could specify a bunch of columns of equal width with the * syntax of the array package:

Code: Select all

\begin{array}{*4{C{2em}}}

You still have once to specify a width for all columns. However, the definition could be changed to take the widest cell entry as argument and adjusting the columns matching to it, using \settowidth.

Stefan

[Cham]

Wow !

Thanks Stefan, it works like a charm !