lute
  distance in the x-dimension.  For <code>method="range"</code>, the width is
  expressed as a fraction of the x-range.  In both cases, <code>pts</code>
  specifies the points at which evaluation of <code>fun</code> occurs.  When
  <code>pts</code> is omitted, <code>n</code> x values equally spaced along the x
  range are used.</p>
<p>The second technique uses windows containing  k neighboring points.  The
  (x,y) pairs are sorted by the x-values and the nearest k/2 points with
  higher x values and th