title: Swift tuple(Double,Double) prints strange result
body: <p>I print two tuples in the Xcode playground. But I get a strange result, see the following code snippet and the print result:</p>
  
  <p><strong>Code Snippet:</strong></p>
  
  <pre><code>let x : (Double,Double) = (1.2,1.3)
  print(x)
  
  let y : (Double,Double) = (1.2,3.1)
  print(y)
  </code></pre>
  
  <p><strong>Print Result:</strong></p>
  
  <pre><code>(1.2, 1.3)
  (1.2, 3.1000000000000001)
  </code></pre>
  
  <p>Why it prints the <code>3.1000000000000001</code> which is <strong>NOT</strong> the actual value (3.1) I set for the tuple? </p>
  
  <p>In the meantime, the <code>1.3</code> is printed out correctly.</p>
  
  <p><strong>My Swift compiler version info:</strong></p>
  
  <pre><code>Apple Swift version 3.0.1 (swiftlang-800.0.58.6 clang-800.0.42.1)
  Target: x86_64-apple-macosx10.9
  </code></pre>