How to create augmented matrix in iBook Author using LaTeX

Question

I am very new to LaTeX so please bear with me if my question is rudimentary. I searched through other questions and while this question has been answered the solutions provided did not work for me, the solutions specifically at What's the best way make an "augmented" coefficient matrix? did not work in iBook Author. This question is how to make an augmented matrix in iBook Author which has minimal support for LaTeX. I am working in iBook Author and am trying to add an augmented matrix. I can get the matrix to display but not the horizontal line. The use of "array" has not worked for me as it is not supported by iBook Author. In iBook Author, there is no need to enter \documentclass, \begin{document}, etc. which is why it is not included in my example.

This is what I use to get the matrix but I need it to be an augmented matrix with a continuous vertical line separating the 4th digit in each row:

\begin{bmatrix}
4 & 8 & -12 & 4 \\
3 & 5 & 6 & 7 \\
2 & 5 & 3 & 8 \\
\end{bmatrix}

I have tried using "array" as well as "ccc|c" and nothing has worked. Any help provided would be greatly appreciated. Thank you.

Please see the screen cap below from the text file, created using Word for reference to what I am trying to achieve.

Answer 1

You should always post a full document with \documentclass, \begin{document} and \end{document}. In other words, a MWE (Minimal Working Example).

That said, the following works for me:

\documentclass[a4paper]{report}
\usepackage{amsmath}

\begin{document}
\[\left[\begin{array}{ccc|c}
a & b & c & d \\
e & f & g & h \\
i & j & k & l \\
m & n & o & p
\end{array}\right]\]
\end{document}

array is the enviroment creating the matrix. ccc|c means three center-aligned columns, with a vertical bar between third and fourth. \left and \right are to make tall brackets, without them the [] do not scale and stay very short.

As @egreg notes, adding @{} before the first c and after the last one removes the "padding space" between the brackets and the matrix, and is therefore advisable.

Update

@Benjamin points out in a comment that array may not be supported by iBook Author. Since iBook Author seems to have partial support of MathML, I posted a spam question on Math.SE to get the MathML code for the above, which is:

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <mo>[</mo>
    <mtable columnalign="center center center center" rowspacing="4pt" columnspacing="1em" columnlines="none none solid">
      <mtr>
        <mtd>
          <mi>a</mi>
        </mtd>
        <mtd>
          <mi>b</mi>
        </mtd>
        <mtd>
          <mi>c</mi>
        </mtd>
        <mtd>
          <mi>d</mi>
        </mtd>
      </mtr>
      <mtr>
        <mtd>
          <mi>e</mi>
        </mtd>
        <mtd>
          <mi>f</mi>
        </mtd>
        <mtd>
          <mi>g</mi>
        </mtd>
        <mtd>
          <mi>h</mi>
        </mtd>
      </mtr>
      <mtr>
        <mtd>
          <mi>i</mi>
        </mtd>
        <mtd>
          <mi>j</mi>
        </mtd>
        <mtd>
          <mi>k</mi>
        </mtd>
        <mtd>
          <mi>l</mi>
        </mtd>
      </mtr>
      <mtr>
        <mtd>
          <mi>m</mi>
        </mtd>
        <mtd>
          <mi>n</mi>
        </mtd>
        <mtd>
          <mi>o</mi>
        </mtd>
        <mtd>
          <mi>p</mi>
        </mtd>
      </mtr>
    </mtable>
    <mo>]</mo>
  </mrow>
</math>

The spam thing is now deleted. Note, however, that bmatrix isn't supported either, so perhaps it is a good idea to move to actual LaTeX and use the solution above.