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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from ellipord.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="ellipord" xml:lang="en"
xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns:ns3="http://www.w3.org/1999/xhtml"
xmlns:mml="http://www.w3.org/1998/Math/MathML"
xmlns:scilab="http://www.scilab.org"
xmlns:db="http://docbook.org/ns/docbook">
<refnamediv>
<refname>ellipord</refname>
<refpurpose>Minimum filter order of a digital elliptic/Cauer filter with the desired response characteristics. </refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>
n = ellipord(Wp, Ws, Rp, Rs)
[n, Wp] = ellipord(Wp, Ws, Rp, Rs)
</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry><term>Wp:</term>
<listitem><para> scalar or vector of length 2 (passband edge(s)), all elements must be in the range [0,1]</para></listitem></varlistentry>
<varlistentry><term>Ws:</term>
<listitem><para> scalar or vector of length 2 (stopband edge(s)), all elements must be in the range [0,1]</para></listitem></varlistentry>
<varlistentry><term>Rp:</term>
<listitem><para> passband ripple in dB.</para></listitem></varlistentry>
<varlistentry><term>Rs:</term>
<listitem><para> stopband attenuation in dB.</para></listitem></varlistentry>
<varlistentry><term>n:</term>
<listitem><para> Minimum order of filter satisfying given specs.</para></listitem></varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para>
This function computes the minimum filter order of an elliptic filter with the desired response characteristics.</para>
<para>Stopband frequency ws and passband frequency wp specify the the filter frequency band edges.</para>
<para>Frequencies are normalized to the Nyquist frequency in the range [0,1].</para>
<para>Rp is measured in decibels and is the allowable passband ripple and Rs is also measured in decibels and is the minimum attenuation in the stop band.</para>
<para>If ws>wp then the filter is a low pass filter. If wp>ws, then the filter is a high pass filter.</para>
<para>If wp and ws are vectors of length 2, then the passband interval is defined by wp and the stopband interval is defined by ws.</para>
<para>If wp is contained within the lower and upper limits of ws, the filter is a band-pass filter. If ws is contained within the lower and upper limits of wp, the filter is a band-stop or band-reject filter.
</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
Wp = [60 200]/500;
Ws = [50 250]/500;
Rp = 3;
Rs = 40;
[n,Wp] = ellipord(Wp,Ws,Rp,Rs)
]]></programlisting>
</refsection>
</refentry>
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