docsrc/xlisp/xlisp-doc/reference/interpolate.htm


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<html><head><title>XLISP interpolate</title>

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</head>

<body>

<a href="../start.htm">Nyquist / XLISP 2.0</a>&nbsp; -&nbsp;
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>

<hr>

<h1>interpolate</h1>

<hr>

<p><table cellpadding="0" cellspacing="0" style="margin-left:10px"><tbody>
<tr valign="top">
  <td><nobr>Type:</nobr></td>
  <td><nobr>&nbsp;&nbsp;-&nbsp;&nbsp;</nobr></td>
  <td width="100%"><nobr>Lisp function (closure)</nobr></td>
</tr>
<tr valign="top">
  <td><nobr>Source:</nobr></td>
  <td><nobr>&nbsp;&nbsp;-&nbsp;&nbsp;</nobr></td>
  <td width="100%"><nobr>xm.lsp</nobr></td>
</tr>
</tbody></table></p>

<h2>Syntax</h2>

<p><div class="box">

<dl>
<dt><nobr>(interpolate <i>x x1 y1 x2 y2</i>)</nobr></dt>
<dd><i>x</i>, <i>x1</i>, <i>y1</i>, <i>x2</i>, <i>y2</i> - integer or floating point numbers<br>
returns - the 'y' value corresponding to 'x'</dd>
</dl>

</div></p>

<p>In Nyquist, 'interpolate' is implemented as a Lisp function:</p>

<pre class="example">
(defun <font color="#0000CC">interpolate</font> (x x1 y1 x2 y2)
  (cond ((= x1 x2) x1)
        (t (+ y1 (* (- x x1) (/ (- y2 y1) (- x2 (float x1))))))))
</pre>

<h2>Description</h2>

<p>The 'interpolate' function linearly interpolates [or extrapolates]
between points <nobr>(x1, y1)</nobr> and <nobr>(x2, y2)</nobr> to compute
the <nobr>'y' value</nobr> corresponding <nobr>to 'x'</nobr>.</p>

<h2>Examples</h2>

<pre class="example">

</pre>

<p><nobr>&nbsp;&nbsp;<a href="#top">Back to Top</nobr></a></p>

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