title: Implement a matrix with another matrix in F#
body: <p>I have the first matrix which should account for each users (in lines) which products (in columns) they like.
  Let's take 3 users and 5 products.
  No user liked a product, so my matrix ILike equals a nul matrix :</p>
  
  <pre><code>let matrixILike = [[0.; 1.;2.;3.]
                     [1.;0.;0.;0.]
                     [2.;0.;0.;0.]
                     [3.;0.;0.;0.]
                     [4.;0.;0.;0.]
                     [5.;0.;0.;0.]]
  </code></pre>
  
  <p>Now  user 1 likes product 2 and user 3 likes product 5 which can be summarized in the following matrix:</p>
  
  <pre><code>let matrixAction = [[1.;2.]
                      [3.;5.]]
  </code></pre>
  
  <p>So I would like to implement the matrix ILike thanks to the matrixAction to obtain a new updated matrixILike like this :</p>
  
  <pre><code>let matrixILike = [[0.; 1.;2.;3.]
                     [1.;0.;0.;0.]
                     [2.;1.;0.;0.]
                     [3.;0.;0.;0.]
                     [4.;0.;0.;0.]
                     [5.;0.;0.;1.]] 
  </code></pre>
  
  <p>I try to do this with a "match with" code but it is not working.</p>
  
  <pre><code>for k = 0 to matrixAction.NumRows - 1 do
              match  (matrixAction.[k,0] , matrixAction.[k,1]) with
              | (matrixILike.[x,0] , matrixILike.[0,y]) -&gt; (matrixILike.[x,y] &lt;- 1.)
              | _ -&gt; (matrixILike.[x,y] &lt;- 0.)
  matrixILike
  </code></pre>
  
  <p>If you have any suggestions I take it. </p>