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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from butter.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="butter" 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>butter</refname>
<refpurpose>This function generates a Butterworth filter.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>
[a, b] = butter (n, w)
[a, b] = butter (n, w, "high")
[a, b] = butter (n, [wl, wh])
[b, a] = butter (n, [wl, wh], "stop")
[a, b, c] = butter (…)
[a, b, c, d] = butter (…)
[…] = butter (…, "s")
</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry><term>n:</term>
<listitem><para> positive integer value</para></listitem></varlistentry>
<varlistentry><term>w:</term>
<listitem><para> positive real value, w in the range [0,1]</para></listitem></varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para>
This is an Octave function.
This function generates a Butterworth filter. Default is a discrete space (Z) filter.
The third parameter takes in low or high, default value is low. The cutoff is pi*Wc radians.
[b,a] = butter(n, [Wl, Wh]) indicates a band pass filter with edges pi*Wl and pi*Wh radians.
[b,a] = butter(n, [Wl, Wh], ’stop’) indicates a band reject filter with edges pi*Wl and pi*Wh radians.
[z,p,g] = butter(...) returns filter as zero-pole-gain rather than coefficients of the numerator and denominator polynomials.
[...] = butter(...,’s’) returns a Laplace space filter, w can be larger than 1.
[a,b,c,d] = butter(...) returns state-space matrices.
</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
[a,b]=butter(3, 0.7)
a =
0.37445 1.12336 1.12336 0.37445
b =
1.00000 1.16192 0.69594 0.13776
]]></programlisting>
</refsection>
</refentry>
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