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[scilab.git] / scilab / modules / cacsd / help / en_US / plot_display / zgrid.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <!--
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10  * This file was originally licensed under the terms of the CeCILL v2.1,
11  * and continues to be available under such terms.
12  * For more information, see the COPYING file which you should have received
13  * along with this program.
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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="zgrid">
17     <refnamediv>
18         <refname>zgrid</refname>
19         <refpurpose>zgrid plot</refpurpose>
20     </refnamediv>
21     <refsynopsisdiv>
22         <title>Calling Sequence</title>
23         <synopsis>
24             zgrid()
25             zgrid(zeta,wn [,colors])
26             zgrid(['new',] zeta,wn [,colors])
27             zgrid(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>0:0.1:1</literal>.
42                     </para>
43                 </listitem>
44             </varlistentry>
45             <varlistentry>
46                 <term>wn</term>
47                 <listitem>
48                     <para>array of normalized natural frequencies (factors of
49                         π/dt).  Only values in <literal>[0 1]</literal> are taken
50                         into account. The default value is
51                         <literal>0:0.1:1</literal>.
52                     </para>
53                 </listitem>
54             </varlistentry>
55             <varlistentry>
56                 <term>colors</term>
57                 <listitem>
58                     <para>a scalar or an 2 element array  with integer values (color index).</para>
59                 </listitem>
60             </varlistentry>
61         </variablelist>
62     </refsection>
63     <refsection>
64         <title>Description</title>
65         <para>
66             plots z-plane grid lines: lines of constant damping factor
67             (selection given by <literal>zeta</literal>) and natural frequency
68             (selection given by <literal>wn</literal>) are drawn in within the
69             unit Z-plane circle.
70         </para>
71         <para>
72             Iso-frequency curves are shown in on the interval
73             [0,%pi/dt].
74         </para>
75         <para>
76             The <literal>colors</literal> argument may be used to assign a
77             color for constant damping ratio curves
78             (<literal>colors(2)</literal>) and for frequency curves
79             (<literal>colors(1)</literal>).
80         </para>
81         <para>
82             The <literal>zgrid</literal> function is often used to draw a grid
83             for evens root locus of continuous time linear systems. In such a
84             case the <literal>zgrid</literal> function should be called after
85             the call to <link linkend="evans">evans</link>. For continuous time linear
86             systems one should use <link linkend="sgrid">sgrid</link> function instead.
87         </para>
88         <para>
89             The optional argument <literal>'new'</literal> can be used to
90             erase the graphic window before plotting the grid.
91         </para>
92     </refsection>
93     <refsection>
94         <title>Examples</title>
95         <programlisting role="example"><![CDATA[
96     //zgrid
97     clf();zgrid(0:0.2:1,[0.2 0.6 0.8 1])
98     ]]></programlisting>
99         <para>
100             <scilab:image>
101                 zgrid(0:0.2:1,[0.2 0.6 0.8 1])
102             </scilab:image>
103         </para>
104         <programlisting role="example"><![CDATA[
105     //zgrid with discrete time system  root locus
106     z=poly(0,'z')
107     H=syslin(0.01,(0.54-1.8*z+2.9*z^2-2.6*z^3+z^4)/(0.8+0.78*z-0.1*z^2+0.9*z^3+z^4))
108     clf();evans(H,1000);zgrid(0:0.1:0.5)
109
110     ]]></programlisting>
111         <para>
112             <scilab:image localized="true">
113                 z=poly(0,'z')
114                 H=syslin(0.01,(0.54-1.8*z+2.9*z^2-2.6*z^3+z^4)/(0.8+0.78*z-0.1*z^2+0.9*z^3+z^4))
115                 clf();evans(H,1000);zgrid(0:0.1:0.5)
116             </scilab:image>
117         </para>
118         
119     </refsection>
120     <refsection role="see also">
121         <title>See Also</title>
122         <simplelist type="inline">
123             <member>
124                 <link linkend="evans">evans</link>
125             </member>
126             <member>
127                 <link linkend="sgrid">sgrid</link>
128             </member>
129             <member>
130                 <link linkend="freson">freson</link>
131             </member>
132             <member>
133                 <link linkend="datatips">datatips</link>
134             </member>
135         </simplelist>
136     </refsection>
137 </refentry>