title: What is the internal method System.Double.IsNegative() for in C#?
body: <p>While browsing the source for <code>System.Double</code>, I came across this method:</p>
  
  <pre><code>[SecuritySafeCritical]
  internal static unsafe bool IsNegative(double d)
  {
    return (*(long*) &amp;d &amp; long.MinValue) == long.MinValue;
  }
  </code></pre>
  
  <p>It doesn't seem to be used anywhere in the <code>System.Double</code> struct. Is it used somewhere else?</p>
  
  <p>As I don't have the full source of the C# standard library on my machine, I can't simply browse references to it via Visual Studio. I also found <a href="https://docs.microsoft.com/en-us/dotnet/api/system.double.isnegative?view=netstandard-2.1" rel="nofollow noreferrer">this API documentation for it</a>, but it doesn't describe why one might want to use it.</p>