title: Sympy - Display Full Equation in Dense Matrix Form
body: <p>I am attempting to use <a href="http://sympy.org/en/index.html?utm_source=%5Bdeliciuos%5D&amp;utm_medium=twitter" rel="nofollow noreferrer">Sympy</a> to decompose estimation procedures within the IPython Notebook.  It would be very useful to be able to accompany data manipulations with the full linear equation display at each step.  To take a simple regression example, I have the following setup:</p>
  
  <pre><code>from sympy import *
  from sympy.abc import epsilon
  
  y=MatrixSymbol('y',5,1)
  x=MatrixSymbol('x',5,2)
  b=MatrixSymbol('b',2,1)
  e=MatrixSymbol('epsilon',5,1)
  </code></pre>
  
  <p>I can print each of the components...</p>
  
  <pre><code>y.as_explicit()
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/R9vdY.png" alt="enter image description here"></p>
  
  <pre><code>(b*x).as_explicit()
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/JDtQu.png" alt="enter image description here"></p>
  
  <pre><code>e.as_explicit()
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/LGYig.png" alt="enter image description here"></p>
  
  <p>...but I have not been able to find, however, a method in Sympy that allows for the full equation to be displayed (the following was rendered with an <a href="http://www.codecogs.com/latex/eqneditor.php" rel="nofollow noreferrer">online latex editor</a>):</p>
  
  <p><img src="https://i.stack.imgur.com/xnQJC.png" alt="enter image description here"></p>
  
  <p>Basically any time I use an equals operator it is reasonably taken as assignment, and addition operators convert the <strong>MatrixSymbol</strong> into a <strong>MatAdd</strong> object, which does not support the <code>as_explict()</code> method. Any thoughts on this issue would be appreciated.</p>