From: astroelectronic@t-online.de   
      
   Phil,   
      
   my question in other words: If I begin with horizontal polarized light   
   (formula 6.20) and then rotate either the observer or the light source by 90   
   degrees, why is the result not equal to your formula 6.21 ?   
      
   The left matrix is R(90) and the right matrix is formula 6.20   
      
   [ 0 1 ] * [ 1 0 ] = [  0 0 ]   
   [-1 0 ]   [ 0 0 ]   [ -1 0 ]   
      
   Michael   
      
   --- SoupGate-Win32 v1.05   
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