Massive indent of all codes:
[scilab.git] / scilab / modules / differential_equations / help / en_US / diff.xml
1         <?xml version="1.0" encoding="UTF-8"?>
2     <!--
3  * Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
4  * Copyright (C) 2008 - INRIA
5  * 
6  * This file must be used under the terms of the CeCILL.
7  * This source file is licensed as described in the file COPYING, which
8  * you should have received as part of this distribution.  The terms
9  * are also available at    
10  * http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
11  *
12  -->
13     <refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:ns5="http://www.w3.org/1999/xhtml" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" xmlns:scilab="http://www.scilab.org" xml:id="diff" xml:lang="en">
14         <refnamediv>
15             <refname>diff</refname>
16             <refpurpose>Difference and discrete derivative</refpurpose>
17         </refnamediv>
18         <refsynopsisdiv>
19             <title>Calling Sequence</title>
20             <synopsis>y=diff(x)
21                 y=diff(x [,n [,dim]])
22             </synopsis>
23         </refsynopsisdiv>
24         <refsection>
25             <title>Arguments</title>
26             <variablelist>
27                 <varlistentry>
28                     <term>x</term>
29                     <listitem>
30                         <para>vector or matrix (real, complex, sparse or polynomial)</para>
31                     </listitem>
32                 </varlistentry>
33                 <varlistentry>
34                     <term>n</term>
35                     <listitem>
36                         <para>integer the order of differentiation</para>
37                     </listitem>
38                 </varlistentry>
39                 <varlistentry>
40                     <term>dim</term>
41                     <listitem>
42                         <para>integer or character string with values "r","c" and "*"</para>
43                     </listitem>
44                 </varlistentry>
45                 <varlistentry>
46                     <term>y</term>
47                     <listitem>
48                         <para>scalar or vector/matrix</para>
49                     </listitem>
50                 </varlistentry>
51             </variablelist>
52         </refsection>
53         <refsection>
54             <title>Description</title>
55             <para>
56                 <literal>y=diff(x)</literal> compute the difference function
57                 <literal>y=x(2:$)-x(1:$-1)</literal>
58             </para>
59             <para>
60                 <literal>diff(x,n,dim)</literal> is the <literal>n</literal>th
61                 difference function along dimension <literal>dim</literal>.
62             </para>
63             <para>
64                 <literal>diff(x,n,"*")</literal> is equivalent to
65                 <literal>diff(x(:),n)</literal>.
66             </para>
67             <para>
68                 Default value for <literal>n</literal> is 1. Default value for
69                 <literal>dim</literal> is <literal>"*"</literal>.
70             </para>
71             <para>
72                 <literal>dim='r'</literal> is equivalent to <literal>dim=1</literal>
73                 and <literal>dim='c'</literal> is equivalent to
74                 <literal>dim=2</literal>.
75             </para>
76         </refsection>
77         <refsection>
78             <title>Examples</title>
79             <programlisting role="example"><![CDATA[ 
80 v=(1:8)^3;
81 diff(v)
82 diff(v,3)
83
84 A=[(1:8)^2
85    (1:8)^3
86    (1:8)^4];
87
88 diff(A,3,2)
89
90 //approximate differentiation
91 step=0.001
92 t=0:step:10;
93 y=sin(t);
94 dy=diff(sin(t))/step; //approximate differentiation of sine function
95 norm(dy-cos(t(1:$-1)),%inf)
96  ]]></programlisting>
97         </refsection>
98         <refsection role="see also">
99             <title>See Also</title>
100             <simplelist type="inline">
101                 <member>
102                     <link linkend="derivative">derivative</link>
103                 </member>
104                 <member>
105                     <link linkend="numdiff">numdiff</link>
106                 </member>
107             </simplelist>
108         </refsection>
109         
110     </refentry>