Text Formatting ⇒ newcommand for 4x4 matrix

[centguy]

Hi.

I am happily using

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\newcommand{\mtwo}[4]{{\left( \begin{array}{cc} #1 & #2 \\ #3 & #4 \end{array} \right)} }
\newcommand{\mthree}[9]{
{\left( \begin{array}{ccc} #1 & #2 & #3  \\ #4 & #5 & #6 \\ #7 & #8 & #9 \end{array} \right)} }

to quickly get 2x2 or 3x3 matrices. Just input either 4 numbers
or 9 numbers.

Now, I need to deal with 4x4 matrices quite a lot, but the above tricks don't work
anymore since the maximum #9 is used.

How can I define \mfour that takes in 16 arguments ?

Thanks!

[localghost]

The 9-argument limit for commands can be evaded [1]. But instead of new commands it might be better to use the matrix environments from amsmath.

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\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{mathtools}  % loads »amsmath«

\begin{document}
  \[
    \begin{pmatrix}
       1 &  2 &  3 &  4 \\
       5 &  6 &  7 &  8 \\
       9 & 10 & 11 & 12 \\
      13 & 14 & 15 & 16
    \end{pmatrix}
  \]
\end{document}

The definition of new commands wouldn't make the input shorter here.

[1] UK TeX FAQ – How to break the 9-argument limit


Thorsten

[centguy]

Thanks. I think I solved this by
creating a file called `mfour' that contains

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\left( \begin{array}{cccc}
\twobyfourN
{ }{ }{ }{ }
{ }{ }{ }{ }
\twobyfourN
{ }{ }{ }{ }
{ }{ }{ }{ }
\end{array} \right)

where

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\newcommand{\twobytwoN}[4]{ #1 & #2 \\ #3 & #4\\ }

Now, every time I need a 4-by-4 matrix, I use vi to read in mfour,
then just fill in the entries, without even have to type lots of
{} !

I am pleased with this solution. But others might have other solution.

I am now using similar mthree and mtwo to get 3x3 and 2x2 matrices
using the same shortcuts.

Just to share my thoughts.