title: std::isfinite on MSVC
body: <p>The C++11 and C11 standard define the
  <a href="http://en.cppreference.com/w/cpp/numeric/math/isfinite" rel="noreferrer">std::isfinite</a>
  function. Visual Studio 2012 doesn't seem to provide it as part of the
  <code>cmath</code> or <code>math.h</code>, but has <code>amp_math.h</code> which
  <a href="http://msdn.microsoft.com/en-us/library/hh308288.aspx" rel="noreferrer">seems to provide this function</a>. </p>
  
  <p>Is the <code>isfinite</code> interchangeable with <code>std::isfinite</code>? The
  documentation doesn't talk about the behavior when called with <code>NAN</code>
  and I don't have a VS compiler to test this.</p>