title: Interpolation on a Curve in R
body: <p>I have a dataset called <code>dataframe</code> (a 2d table) and a best fit curve as: </p>
  
  <pre><code>scatter.smooth(dataframe, xlab="", ylab="") 
  </code></pre>
  
  <p>What code would I need to realize and evaluate (get numerical value of) a Y value on that best fit curve at a single x value?</p>