title: Why compile-time floating point calculations might not have the same results as run-time calculations?
body: <p>In <a href="https://www.youtube.com/watch?v=fZjYCQ8dzTc&amp;feature=youtu.be&amp;t=2013" rel="nofollow noreferrer">constexpr: Introduction</a>, the speaker mentioned &quot;Compile-time floating point calculations might not have the same results as runtime calculations&quot;:
  <a href="https://i.stack.imgur.com/OCEcx.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OCEcx.jpg" alt="enter image description here" /></a></p>
  <p>And the reason is related to &quot;cross-compiling&quot;.</p>
  <p>Honestly, I can't get the idea clearly. IMHO, different platforms may also have different implementation of integers.</p>
  <p>Why does it only affect floating points? Or I miss something?</p>