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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from freqz.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="freqz" 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>freqz</refname>
<refpurpose>This function returns the complex frequency response H of the rational IIR filter whose numerator and denominator coefficients are B and A, respectively.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>
[H, W] = freqz(B, A, N, "whole")
[H, W] = freqz(B)
[H, W] = freqz(B, A)
[H, W] = freqz(B, A, N)
H = freqz(B, A, W)
[H, W] = freqz(..., FS)
freqz(...)
</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry><term>B, A, N:</term>
<listitem><para> Integer or Vector</para></listitem></varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para>
Return the complex frequency response H of the rational IIR filter whose numerator and denominator coefficients are B and A, respectively.
</para>
<para>
The response is evaluated at N angular frequencies between 0 and 2*pi.
</para>
<para>
The output value W is a vector of the frequencies.
</para>
<para>
If A is omitted, the denominator is assumed to be 1 (this corresponds to a simple FIR filter).
</para>
<para>
If N is omitted, a value of 512 is assumed. For fastest computation, N should factor into a small number of small primes.
</para>
<para>
If the fourth argument, "whole", is omitted the response is evaluated at frequencies between 0 and pi.
</para>
<para>
'freqz (B, A, W)'
</para>
<para>
Evaluate the response at the specific frequencies in the vector W. The values for W are measured in radians.
</para>
<para>
'[...] = freqz (..., FS)'
</para>
<para>
Return frequencies in Hz instead of radians assuming a sampling rate FS. If you are evaluating the response at specific frequencies W, those frequencies should be requested in Hz rather than radians.
</para>
<para>
'freqz (...)'
</para>
<para>
Plot the magnitude and phase response of H rather than returning them.
</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
H = freqz([1,2,3], [4,3], [1,2,5])
ans =
0.4164716 - 0.5976772i - 0.4107690 - 0.2430335i 0.1761948 + 0.6273032i
]]></programlisting>
</refsection>
</refentry>
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