Introduced the notion of a matrix and the operations of addition,
subtraction and multiplication. <br>
      <br>
For more background on matrix addition look at the wikipedia page <a
 href="http://en.wikipedia.org/wiki/Matrix_addition">here</a>. <br>
      <br>
For more background on matrix multiplication look at the wikipedia page
      <a href="http://en.wikipedia.org/wiki/Matrix_multiplication">here</a>.
<br><br>
See Section 8.1 of Lawson's book for more details and examples on matrix arithmetic.