<?xml version="1.0" encoding="UTF-8"?>
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Copyright (c) 1996 by CNRS (France).
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<refentry xml:id="gdpower" xml:lang="en"
          xmlns="http://docbook.org/ns/docbook"
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          xmlns:scilab="http://www.scilab.org"
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          xmlns:mml="http://www.w3.org/1998/Math/MathML"
          xmlns:db="http://docbook.org/ns/docbook">

  <refnamediv>
    <refname>gdpower</refname>
	<refpurpose>Signal with power-law group delay</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <title>Calling Sequence</title>
    <synopsis>
      [X,GPD,F] = gspower(N, K, C)
    </synopsis>
  </refsynopsisdiv>

  <refsection>
    <title>Parameters</title>
    <variablelist>
      <varlistentry>
        <term>N  :</term>
        <listitem>
          <para>an even positive integer:  number of points in time</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>K  :</term>
        <listitem>
          <para>a real scalar: the degree of the power-law (default : 0)</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>C  :</term>
        <listitem>
          <para>a real non zero scalar: the  rate-coefficient of the power-law group delay. (default : 1)</para>
        </listitem>
      </varlistentry>
      
      
      <varlistentry>
        <term>X   :</term>
        <listitem>
          <para>a real column vector: the modulated signal samples</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>GPD :</term>
        <listitem><para>a real row vector (length : round(N/2)-1): the group delay (length : round(N/2)-1)</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>F   :</term>
        <listitem>
          <para>a real row vector (length : round(N/2)-1): the frequency bins</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsection>

  <refsection>
    <title>Description</title>
    <para>
      generates a signal with a power-law group delay of the form tx(f) = T0 + C*f^(K-1).
      The output signal is of unit energy.
    </para>
  </refsection>

  <refsection>
    <title>Examples</title>
    <programlisting role="example"><![CDATA[
    [sig,gpd,f] = gdpower(256,1/2); 
    clf
    subplot(211); plot(sig);
    subplot(212); plot(gpd,f);
    ]]></programlisting>
    <scilab:image><![CDATA[
    [sig,gpd,f]=gdpower(256,1/2); 
    clf;
    subplot(211);plot(sig);
    subplot(212);plot(gpd,f);
    ]]></scilab:image>
  </refsection>

  <refsection role="see also">
    <title>See also</title>
    <simplelist type="inline">
      <member><link linkend="fmpower">fmpower</link></member>
    </simplelist>
  </refsection>

  <refsection>
    <title>Authors</title>
    <simplelist type="vert">
      <member>H. Nahrstaedt - Aug 2010</member>
      <member>O. Lemoine - April, July 1996</member>
    </simplelist>
  </refsection>
</refentry>
