a79de11393a702b070b2d43a4a3ebf27013c3c77
[scilab.git] / scilab / modules / cacsd / help / en_US / calfrq.xml
1 <?xml version="1.0" encoding="ISO-8859-1"?>
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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:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" version="5.0-subset Scilab" xml:lang="en" xml:id="calfrq">
14   <info>
15     <pubdate>$LastChangedDate$</pubdate>
16   </info>
17   <refnamediv>
18     <refname>calfrq</refname>
19     <refpurpose> frequency response discretization</refpurpose>
20   </refnamediv>
21   <refsynopsisdiv>
22     <title>Calling Sequence</title>
23     <synopsis>[frq,split]=calfrq(h,[fmin,fmax])</synopsis>
24   </refsynopsisdiv>
25   <refsection>
26     <title>Parameters</title>
27     <variablelist>
28       <varlistentry>
29         <term>h</term>
30         <listitem>
31           <para>SISO linear system (<literal>syslin</literal> list)</para>
32         </listitem>
33       </varlistentry>
34       <varlistentry>
35         <term>fmin,fmax</term>
36         <listitem>
37           <para>real scalars (min and max frequencies)</para>
38         </listitem>
39       </varlistentry>
40       <varlistentry>
41         <term>frq</term>
42         <listitem>
43           <para>row vector (discretization of interval)</para>
44         </listitem>
45       </varlistentry>
46       <varlistentry>
47         <term>split</term>
48         <listitem>
49           <para>vector of frq splitting points indexes</para>
50         </listitem>
51       </varlistentry>
52     </variablelist>
53   </refsection>
54   <refsection>
55     <title>Description</title>
56     <para>
57     frequency response discretization ; <literal>frq</literal> is the discretization of  
58     <literal>[fmin,fmax]</literal> 
59     such that the peaks in the frequency response are well represented.</para>
60     <para>
61     Default values for <literal>fmin</literal> and <literal>fmax</literal> are
62     <literal>1.d-3</literal>, <literal>1.d+3</literal> if <literal>h</literal> is continuous-time
63     or <literal>1.d-3</literal>, <literal>1/(2*h('dt'))</literal> if <literal>h</literal> is discrete-time.</para>
64     <para>
65     Singularities are located between <literal>frq(split(k))</literal> and <literal>frq(split(k)+1)</literal>
66     for <literal>k&gt;1</literal>.</para>
67   </refsection>
68   <refsection>
69     <title>Examples</title>
70     <programlisting role="example"><![CDATA[
71
72 s=poly(0,'s')
73 h=syslin('c',(s^2+2*0.9*10*s+100)/(s^2+2*0.3*10.1*s+102.01))
74 h1=h*syslin('c',(s^2+2*0.1*15.1*s+228.01)/(s^2+2*0.9*15*s+225)) 
75 [f1,spl]=calfrq(h1,0.01,1000);
76 rf=repfreq(h1,f1);
77 plot2d(real(rf)',imag(rf)')
78  
79   ]]></programlisting>
80   </refsection>
81   <refsection>
82     <title>See Also</title>
83     <simplelist type="inline">
84       <member>
85         <link linkend="bode">bode</link>
86       </member>
87       <member>
88         <link linkend="black">black</link>
89       </member>
90       <member>
91         <link linkend="nyquist">nyquist</link>
92       </member>
93       <member>
94         <link linkend="freq">freq</link>
95       </member>
96       <member>
97         <link linkend="repfreq">repfreq</link>
98       </member>
99       <member>
100         <link linkend="logspace">logspace</link>
101       </member>
102     </simplelist>
103   </refsection>
104 </refentry>