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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from freqs.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="freqs" 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>freqs</refname>
<refpurpose>Compute the s-plane frequency response of the IIR filter.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>
h = freqs (b, a, w)
</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry><term>b:</term>
<listitem><para> vector containing the coefficients of the numerator of the filter.</para></listitem></varlistentry>
<varlistentry><term>a:</term>
<listitem><para> vector containing the coefficients of the denominator of the filter.</para></listitem></varlistentry>
<varlistentry><term>w:</term>
<listitem><para> vector containing frequencies</para></listitem></varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para>
This is an Octave function.
It computes the s-plane frequency response of the IIR filter B(s)/A(s) as H = polyval(B,j*W)./polyval(A,j*W).
If called with no output argument, a plot of magnitude and phase are displayed.
</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
B = [1 2];
A = [1 1];
w = linspace(0,4,128);
freqs(B,A,w);
]]></programlisting>
</refsection>
</refentry>
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