title: NaN issue in fortran 90
body: <p>I realize that if you write</p>
  
  <pre><code>    Real (Kind(0.d0))::x,y
      x = sqrt(-1.d0)
      y = sqrt(-1.d0)
      if (x == y) then
         write(*,*)'yep, they are equals', x
      endif
  </code></pre>
  
  <p>It compiles ok using ifort.
  But nothing is written, the conditional is always <em>false</em>, did you notice that? why is this so?</p>