title: Cubic spline extrapolation
body: <p>I have a nice cubic spline code but it is for interpolation only. I need to <a href="http://en.wikipedia.org/wiki/Extrapolation" rel="noreferrer">extrapolate</a> just a little into the future. Does anyone know of a good source of code, not a library, for doing this?</p>
  
  <p><a href="http://www.coastrd.com/basic-cubic-spline-interpolation" rel="noreferrer">This is the code</a> I wrote in basic (now ASM) for interpolation.</p>