title: How far can we trust calculus with infinity?
body: <p>In this simple calculus, all the results are OK :</p>
  <pre><code>program main
  
      real :: x,y,z
      
      x=0.0
      y=1/x; print *,y
      y=log(x); print *,y
      z=0.99; y=z**(1/x); print *,y
      z=1.0; y=z**(1/x); print *,y
      z=1.01; y=z**(1/x); print *,y
      
  end program main
  </code></pre>
  <p>I found it very convenient. Indeed, if X is an array, I have not to do loop check (e.g. <code>x(i)/=0</code>) on array elements to calculate <code>z**(1/x(i))</code>. But I wonder how far can we trust this kind of calculus ?</p>