scilab/modules/signal_processing/help/en_US/zpbutt.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <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="zpbutt">
   3     <refnamediv>
   4         <refname>zpbutt</refname>
   5         <refpurpose> Butterworth analog filter</refpurpose>
   6     </refnamediv>
   7     <refsynopsisdiv>
   8         <title>Calling Sequence</title>
   9         <synopsis>[pols,gain]=zpbutt(n,omegac)</synopsis>
  10     </refsynopsisdiv>
  11     <refsection>
  12         <title>Arguments</title>
  13         <variablelist>
  14             <varlistentry>
  15                 <term>n</term>
  16                 <listitem>
  17                     <para>integer (filter order)</para>
  18                 </listitem>
  19             </varlistentry>
  20             <varlistentry>
  21                 <term>omegac</term>
  22                 <listitem>
  23                     <para>real (cut-off frequency in Hertz)</para>
  24                 </listitem>
  25             </varlistentry>
  26             <varlistentry>
  27                 <term>pols</term>
  28                 <listitem>
  29                     <para>resulting poles of filter</para>
  30                 </listitem>
  31             </varlistentry>
  32             <varlistentry>
  33                 <term>gain</term>
  34                 <listitem>
  35                     <para>resulting gain of filter</para>
  36                 </listitem>
  37             </varlistentry>
  38         </variablelist>
  39     </refsection>
  40     <refsection>
  41         <title>Description</title>
  42         <para>
  43             computes the poles of a Butterworth analog
  44             filter of order <literal>n</literal> and cutoff frequency omegac
  45             transfer function H(s) is calculated by <literal>H(s)=gain/real(poly(pols,'s'))</literal>
  46         </para>
  47     </refsection>
  48     <refsection>
  49         <title>Examples</title>
  50         <programlisting role="example"><![CDATA[
  51 n=7;
  52 omegac=3;
  53 [pols,gain]=zpbutt(n,omegac)
  54  ]]></programlisting>
  55     </refsection>
  56
  57 </refentry>