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ali@0: <!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
ali@0:                "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd"
ali@0: [
ali@0: ]>
ali@0: <chapter id="language-extensions">
ali@0:   <title>Language Extensions</title>
ali@0: 
ali@0:   <para>
ali@0:     These language extensions are provided in the following namespace URI:
ali@0:     <screen>
ali@0: http://www.juiblex.co.uk/ns/libxexpr
ali@0:     </screen>
ali@0:     People using this namespace are encouraged to use the libxexpr namespace
ali@0:     prefix.
ali@0:   </para>
ali@0: 
ali@0:   <sect1 id="libxexpr-pi">
ali@0:     <title>Function &lt;pi&gt;</title>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Synopsis</title>
ali@0: 	<para>
ali@0: 	  &lt;pi&gt; returns the value of π.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Arguments</title>
ali@0: 	<para>
ali@0: 	  &lt;pi&gt; takes no arguments.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Return Values</title>
ali@0: 	<para>
ali@0: 	  &lt;pi&gt; returns the value of π.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <example>
ali@0:       <programlisting>
ali@0: &lt;libxexpr:pi/&gt; ≅ &lt;float&gt;3.14&lt;/float&gt;<!--
ali@0:    --></programlisting>
ali@0:     </example>
ali@0:   </sect1>
ali@0: 
ali@0:   <sect1 id="libxexpr-sin">
ali@0:     <title>Function &lt;sin&gt;</title>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Synopsis</title>
ali@0: 	<para>
ali@0: 	  &lt;sin&gt; computes the sine function.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Arguments</title>
ali@0: 	<para>
ali@0: 	  &lt;sin&gt; takes one argument: x. If no argument is given, an error
ali@0: 	  occurs.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Return Values</title>
ali@0: 	<para>
ali@0: 	  &lt;sin&gt; returns the sine of its argument, given in radians.
ali@0: 	  If the argument does not evaluate to a finite number,
ali@0: 	  &lt;sin&gt; returns an indeterminate result.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <example>
ali@0:       <programlisting>
ali@0: &lt;libxexpr:sin&gt;
ali@0:   &lt;divide&gt;
ali@0:     &lt;libxexpr:pi/&gt;
ali@0:     2
ali@0:   &lt;/divide&gt;
ali@0: &lt;/libxexpr:sin&gt; --> &lt;float&gt;1&lt;/float&gt;<!--
ali@0:    --></programlisting>
ali@0:     </example>
ali@0:   </sect1>
ali@0: 
ali@0:   <sect1 id="libxexpr-atan">
ali@0:     <title>Function &lt;atan&gt;</title>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Synopsis</title>
ali@0: 	<para>
ali@0: 	  &lt;atan&gt; computes the arc tangent function.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Arguments</title>
ali@0: 	<para>
ali@0: 	  &lt;atan&gt; takes two arguments: x and y. The y argument defaults to
ali@0: 	  1. If the x argument is missing, an error occurs.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Return Values</title>
ali@0: 	<para>
ali@0: 	  &lt;atan&gt; returns the principal value of the arc tangent of its
ali@0: 	  argument(s) in radians. If either argument is indeterminate,
ali@0: 	  the result is also indeterminate.
ali@0: 	</para>
ali@0: 	
ali@0: 	<para>
ali@0: 	  If two arguments are given, &lt;atan&gt; returns the arc tangent of
ali@0: 	  y/x, using the signs of the two arguments to determine the quadrant
ali@0: 	  of the result which will be in the range [-π, π]. If both arguments
ali@0: 	  are 0, the result will also be 0.
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If only one argument is given, &lt;atan&gt; returns the arc tangent of
ali@0: 	  its argument. The result will be in the range [-π/2, π/2].
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <example>
ali@0:       <programlisting>
ali@0: &lt;libxexpr:atan&gt;1 0&lt;/libxexpr:atan&gt; --> &lt;float&gt;0&lt;/float&gt;<!--
ali@0:    --></programlisting>
ali@0:     </example>
ali@0:   </sect1>
ali@0: 
ali@0:   <sect1 id="libxexpr-exp">
ali@0:     <title>Function &lt;exp&gt;</title>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Synopsis</title>
ali@0: 	<para>
ali@0: 	  &lt;exp&gt; computes the base-e exponential function.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Arguments</title>
ali@0: 	<para>
ali@0: 	  &lt;exp&gt; takes zero or one argument: x.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Return Values</title>
ali@0: 	<para>
ali@0: 	  &lt;exp&gt; returns the value of e (the base of natural logarithms)
ali@0: 	  raised to the power of its argument (or just e if no argument is
ali@0: 	  supplied). If the argument does not evaluate to a finite number,
ali@0: 	  &lt;exp&gt; returns an indeterminate result.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <example>
ali@0:       <programlisting>
ali@0: &lt;libxexpr:exp&gt;2&lt;/libxexpr:exp&gt; ≅ &lt;float&gt;7.389&lt;/float&gt;<!--
ali@0:    --></programlisting>
ali@0:     </example>
ali@0:   </sect1>
ali@0: 
ali@0:   <sect1 id="libxexpr-log">
ali@0:     <title>Function &lt;log&gt;</title>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Synopsis</title>
ali@0: 	<para>
ali@0: 	  &lt;log&gt; computes the natural logarithmic function.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Arguments</title>
ali@0: 	<para>
ali@0: 	  &lt;log&gt; takes one argument: x. If no argument is given, an error
ali@0: 	  occurs.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Return Values</title>
ali@0: 	<para>
ali@0: 	  &lt;log&gt; returns the natural logarithm of its argument.
ali@0: 	  If the argument does not evaluate to a positive finite number,
ali@0: 	  &lt;log&gt; returns an indeterminate result.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <example>
ali@0:       <programlisting>
ali@0: &lt;libxexpr:log&gt;
ali@0:   &lt;libxexpr:exp&gt;2&lt;/libxexpr:exp&gt;
ali@0: &lt;/libxexpr:log&gt; --> &lt;float&gt;2&lt;/float&gt;<!--
ali@0:    --></programlisting>
ali@0:     </example>
ali@0:   </sect1>
ali@0: 
ali@0:   <sect1 id="libxexpr-pow">
ali@0:     <title>Function &lt;pow&gt;</title>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Synopsis</title>
ali@0: 	<para>
ali@0: 	  &lt;pow&gt; computes the value of its first argument raised to the
ali@0: 	  power of its second argument.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Arguments</title>
ali@0: 	<para>
ali@0: 	  &lt;pow&gt; takes two arguments: x and y. If fewer arguments are
ali@0: 	  given, an error occurs.
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <simplesect>
ali@0:       <title>Return Values</title>
ali@0: 	<para>
ali@0: 	  &lt;pow&gt; returns the value of x (its first argument) raised to the
ali@0: 	  power of y (its second argument).
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If x is a finite value less than 0, and y is a finite non-integer,
ali@0: 	  &lt;pow&gt; returns an indeterminate result. 
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If the result overflows, &lt;pow&gt; returns an indeterminate result. 
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If result underflows, and is not representable, 0 is returned.
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  Except as specified below, if either argument is indeterminate,
ali@0: 	  the result is also indeterminate.
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If x is 1, the result is 1 (even if y is indeterminate).
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If y is 0, the result is 1 (even if x is indeterminate).
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If x is 0, and y is an odd integer greater than 0, the result is 0.
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If x is 0, and y greater than 0 and not an odd integer, the result
ali@0: 	  is 0.
ali@0: 	</para>
ali@0: 
ali@0: 	<para>
ali@0: 	  If x is 0, and y is less than 0,
ali@0: 	  &lt;pow&gt; returns an indeterminate result. 
ali@0: 	</para>
ali@0:     </simplesect>
ali@0: 
ali@0:     <example>
ali@0:       <programlisting>
ali@0:   &lt;libxexpr:pow&gt;10 2&lt;/libxexpr:pow&gt; --> &lt;float&gt;100&lt;/float&gt;<!--
ali@0:    --></programlisting>
ali@0:     </example>
ali@0:   </sect1>
ali@0: </chapter>