title: Random number generation seemingly not working properly
body: <p>There's a thing that's happening that I don't understand the reason behind.</p>
  
  <p>In Visual Basic, I've got a 2D Integer array that I populate with random numbers. When I do it with Rnd():</p>
  
  <pre><code>For j = 0 To matrix.GetUpperBound(0)
    For i = 0 To matrix.GetUpperBound(1)
      matrix(j, i) = 1 + CType((Rnd() * 50), Integer)
    Next
  Next
  </code></pre>
  
  <p>It always writes the same numbers in the same position in the matrix. </p>
  
  <p>But when I do it with the Random class:</p>
  
  <pre><code>Dim r As Random = New Random()
  For j = 0 To matrica.GetUpperBound(0)
    For i = 0 To matrica.GetUpperBound(1)
      matrica(j, i) = r.Next(0, 100)
    Next
  Next
  </code></pre>
  
  <p>It does what it's supposed to.</p>
  
  <p>I don't understand why in the first case I get the same numbers in the same position every time I run the code.</p>