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[scilab.git] / scilab / modules / cacsd / help / en_US / plot_display / sgrid.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <!--
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12  * For more information, see the COPYING file which you should have received
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16 <refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" xmlns:scilab="http://www.scilab.org"  xml:lang="en" xml:id="sgrid">
17     <refnamediv>
18         <refname>sgrid</refname>
19         <refpurpose>s-plane grid lines.</refpurpose>
20     </refnamediv>
21     <refsynopsisdiv>
22         <title>Calling Sequence</title>
23         <synopsis>
24             sgrid()
25             sgrid(zeta,wn [,colors])
26             sgrid(['new',] zeta,wn [,colors])
27             sgrid(zeta,wn [,'new'] [,colors])
28         </synopsis>
29     </refsynopsisdiv>
30     <refsection>
31         <title>Arguments</title>
32         <variablelist>
33             <varlistentry>
34                 <term>zeta</term>
35                 <listitem>
36                     <para>
37                         array of damping factors. Only values in <literal>[0
38                             1]
39                         </literal>
40                         are taken into account. The default value is
41                         <literal>[0 0.16 0.34 0.5 0.64 0.76 0.86 0.94 0.985
42                             1]
43                         </literal>
44                         .
45                     </para>
46                 </listitem>
47             </varlistentry>
48             <varlistentry>
49                 <term>wn</term>
50                 <listitem>
51                     <para>array of natural frequencies in Hz. only positive values are
52                         taken into account. If not given it is computed by the
53                         program to fit with the boundaries of the plot.
54                     </para>
55                 </listitem>
56             </varlistentry>
57             <varlistentry>
58                 <term>colors</term>
59                 <listitem>
60                     <para>a scalar or an 2 element array  with integer values (color index).</para>
61                 </listitem>
62             </varlistentry>
63         </variablelist>
64     </refsection>
65     <refsection>
66         <title>Description</title>
67         <para>
68             Plots selected curves of constant damping ratio (selection given
69             by <literal>zeta</literal>) and constant natural frequency
70             (selection given by <literal>wn</literal>).
71         </para>
72         <para>
73             The <literal>colors</literal> argument may be used to assign a
74             color for constant damping ratio curves
75             (<literal>colors(2)</literal>) and for constant natural
76             frequency curves (<literal>colors(1)</literal>).
77         </para>
78         <para>
79             The <literal>sgrid</literal> function is often used to draw a grid
80             for evens root locus of continuous time linear systems. In such a
81             case the <literal>sgrid</literal> function should be called after
82             the call to <link linkend="evans">evans</link>. For discrete time linear
83             systems one should use <link linkend="zgrid">zgrid</link> function instead.
84         </para>
85         <para>
86             The optional argument <literal>'new'</literal> can be used to
87             erase the graphic window before plotting the grid.
88         </para>
89     </refsection>
90     <refsection>
91         <title>Examples</title>
92         <programlisting role="example"><![CDATA[
93     //sgrid
94     clf();sgrid(0:0.2:1,[0.2 0.6 1 1.7 2])
95     ]]></programlisting>
96         <para>
97             <scilab:image>
98                 sgrid(0:0.2:1,[0.2 0.6 1 1.7 2])
99             </scilab:image>
100         </para>
101         <programlisting role="example"><![CDATA[
102         H=syslin('c',352*poly(-5,'s')/poly([0,0,2000,200,25,1],'s','c'));
103         clf();evans(H,100);sgrid()
104         ]]></programlisting>
105         <para>
106             <scilab:image localized="true">
107                 H=syslin('c',352*poly(-5,'s')/poly([0,0,2000,200,25,1],'s','c'));
108                 clf();evans(H,100);sgrid()
109             </scilab:image>
110         </para>
111     </refsection>
112     <refsection role="see also">
113         <title>See Also</title>
114         <simplelist type="inline">
115             <member>
116                 <link linkend="evans">evans</link>
117             </member>
118             <member>
119                 <link linkend="zgrid">zgrid</link>
120             </member>
121             <member>
122                 <link linkend="datatips">datatips</link>
123             </member>
124         </simplelist>
125     </refsection>
126 </refentry>