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* Chickadee: (chickadee). Game programming toolkit for Guile.
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<title>Basics (The Chickadee Game Toolkit)</title>
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<span id="Basics"></span><div class="header">
<p>
Next: <a href="Vectors.html" accesskey="n" rel="next">Vectors</a>, Up: <a href="Math.html" accesskey="u" rel="up">Math</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p>
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<hr />
<span id="Basics-1"></span><h4 class="subsection">5.2.1 Basics</h4>
<dl>
<dt id="index-pi">Variable: <strong>pi</strong></dt>
<dd><p>An essential constant for all trigonometry. Pi is the ratio of a
circle’s circumferences to its diameter. Since pi is an irrational
number, the <var>pi</var> in Chickadee is a mere floating point
approximation that is “good enough.”
</p></dd></dl>
<dl>
<dt id="index-pi_002f2">Variable: <strong>pi/2</strong></dt>
<dd><p>Half of <var>pi</var>.
</p></dd></dl>
<dl>
<dt id="index-tau">Variable: <strong>tau</strong></dt>
<dd><p>Twice <var>pi</var>.
</p></dd></dl>
<dl>
<dt id="index-cotan">Procedure: <strong>cotan</strong> <em>z</em></dt>
<dd><p>Return the cotangent of <var>z</var>.
</p></dd></dl>
<dl>
<dt id="index-clamp">Procedure: <strong>clamp</strong> <em>min max x</em></dt>
<dd><p>Restrict <var>x</var> to the inclusive range defined by <var>min</var> and
<var>max</var>. This procedure assumes that <var>min</var> is actually less
than <var>max</var>.
</p></dd></dl>
<dl>
<dt id="index-lerp">Procedure: <strong>lerp</strong> <em>start end alpha</em></dt>
<dd><p>Linearly interpolate the numbers <var>start</var> and <var>end</var> using the
factor <var>alpha</var>, a number in the range [0, 1].
</p></dd></dl>
<dl>
<dt id="index-degrees_002d_003eradians">Procedure: <strong>degrees->radians</strong> <em>degrees</em></dt>
<dd><p>Convert <var>degrees</var> to radians.
</p></dd></dl>
<dl>
<dt id="index-radians_002d_003edegrees">Procedure: <strong>radians->degrees</strong> <em>radians</em></dt>
<dd><p>Convert <var>radians</var> to degrees.
</p></dd></dl>
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