upstream-man-pages/manglsl/atan.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="radians">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>atan</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>atan</refname>
  17         <refpurpose>return the arc-tangent of the parameters</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>genType <function>atan</function></funcdef>
  23                 <paramdef>genType <parameter>y</parameter></paramdef>
  24                 <paramdef>genType <parameter>x</parameter></paramdef>
  25             </funcprototype>
  26         </funcsynopsis>
  27         <funcsynopsis>
  28             <funcprototype>
  29                 <funcdef>genType <function>atan</function></funcdef>
  30                 <paramdef>genType <parameter>y_over_x</parameter></paramdef>
  31             </funcprototype>
  32         </funcsynopsis>
  33     </refsynopsisdiv>
  34     <refsect1 id="parameters"><title>Parameters</title>
  35         <variablelist>
  36         <varlistentry>
  37             <term><parameter>y</parameter></term>
  38             <listitem>
  39                 <para>
  40                     Specify the numerator of the fraction whose arctangent to return.
  41                 </para>
  42             </listitem>
  43         </varlistentry>
  44         <varlistentry>
  45             <term><parameter>x</parameter></term>
  46             <listitem>
  47                 <para>
  48                     Specify the denominator of the fraction whose arctangent to return.
  49                 </para>
  50             </listitem>
  51         </varlistentry>
  52         <varlistentry>
  53             <term><parameter>y_over_x</parameter></term>
  54             <listitem>
  55                 <para>
  56                     Specify the fraction whose arctangent to return.
  57                 </para>
  58             </listitem>
  59         </varlistentry>
  60         </variablelist>
  61     </refsect1>
  62     <refsect1 id="description"><title>Description</title>
  63         <para>
  64             <function>atan</function> returns the angle whose trigonometric arctangent is
  65             <inlineequation><mml:math>
  66                 <!-- eqn: b sub 0: -->
  67                 <mml:mfrac>
  68                     <mml:mrow>
  69                         <mml:mi mathvariant="italic">y</mml:mi>
  70                     </mml:mrow>
  71                     <mml:mrow>
  72                         <mml:mi mathvariant="italic">x</mml:mi>
  73                     </mml:mrow>
  74                 </mml:mfrac>
  75             </mml:math></inlineequation> or <inlineequation><mml:math><mml:mi mathvariant="italic">y_over_x</mml:mi></mml:math></inlineequation>,
  76             depending on which overload is invoked. In the first overload, the signs of <inlineequation><mml:math><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>
  77             and <inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation> are used to determine the quadrant
  78             that the angle lies in. The values returned by <function>atan</function> in this case are in the range
  79             <inlineequation><mml:math>
  80                 <mml:list order="numeric">
  81                     <mml:csymbol><mml:mo>&minus;</mml:mo><mml:pi/></mml:csymbol>
  82                     <mml:pi/>
  83                     </mml:list>
  84             </mml:math></inlineequation>. Results are undefined if <inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation> is zero.
  85         </para>
  86         <para>
  87             For the second overload, <function>atan</function> returns the angle whose tangent is
  88             <inlineequation><mml:math><mml:mi mathvariant="italic">y_over_x</mml:mi></mml:math></inlineequation>. Values
  89             returned in this case are in the range
  90             <inlineequation><mml:math>
  91                 <mml:list order="numeric">
  92                     <mml:mrow>
  93                         <mml:mo>&minus;</mml:mo>
  94                         <mml:mfrac>
  95                             <mml:csymbol><mml:pi/></mml:csymbol>
  96                             <mml:mn>2</mml:mn>
  97                         </mml:mfrac>
  98                     </mml:mrow>
  99                     <mml:mfrac>
 100                         <mml:pi/>
 101                         <mml:mn>2</mml:mn>
 102                     </mml:mfrac>
 103                 </mml:list>
 104             </mml:math></inlineequation>.
 105         </para>
 106     </refsect1>
 107     <refsect1 id="versions"><title>Version Support</title>
 108         <informaltable frame="topbot">
 109             #VARTABLECOLS#
 110                 <thead>
 111                     #FUNCTABLEHEADER#
 112                     <row>
 113                         <entry>atan</entry>#newin11#
 114                     </row>
 115                 </thead>
 116             </tgroup>
 117         </informaltable>
 118     </refsect1>
 119     <refsect1 id="seealso"><title>See Also</title>
 120         <para>
 121             <citerefentry><refentrytitle>sin</refentrytitle></citerefentry>,
 122             <citerefentry><refentrytitle>cos</refentrytitle></citerefentry>,
 123             <citerefentry><refentrytitle>tan</refentrytitle></citerefentry>
 124         </para>
 125     </refsect1>
 126     <refsect1 id="Copyright"><title>Copyright</title>
 127         <para>
 128             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
 129             This material may be distributed subject to the terms and conditions set forth in
 130             the Open Publication License, v 1.0, 8 June 1999.
 131             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 132         </para>
 133     </refsect1>
 134 </refentry>