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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from fir2.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="fir2" 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>fir2</refname>
<refpurpose>Produce an order N FIR filter with arbitrary frequency response M over frequency bands F, returning the N+1 filter coefficients in B.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>
B = fir2(N, F, M)
B = fir2(N, F, M, GRID_N)
B = fir1(N, F, M, GRID_N, RAMP_N)
B = fir1(N, F, M, GRID_N, RAMP_N, WINDOW)
</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry><term>N:</term>
<listitem><para> Integer</para></listitem></varlistentry>
<varlistentry><term>F, M:</term>
<listitem><para> Vector</para></listitem></varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para>
Produce an order N FIR filter with arbitrary frequency response M over frequency bands F, returning the N+1 filter coefficients in B. The vector F specifies the frequency band edges of the filter response and M specifies the magnitude response at each frequency.
</para>
<para>
The vector F must be nondecreasing over the range [0,1], and the first and last elements must be 0 and 1, respectively. A discontinuous jump in the frequency response can be specified by duplicating a band edge in F with different values in M.
</para>
<para>
The resolution over which the frequency response is evaluated can be controlled with the GRID_N argument. The default is 512 or the next larger power of 2 greater than the filter length.
</para>
<para>
The band transition width for discontinuities can be controlled with the RAMP_N argument. The default is GRID_N/25. Larger values will result in wider band transitions but better stopband rejection.
</para>
<para>
An optional shaping WINDOW can be given as a vector with length N+1. If not specified, a Hamming window of length N+1 is used.
</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
fir2 (10, [0, 0.5, 1], [1, 2, 3])
ans =
-0.00130 0.00000 -0.01792 0.00000 -0.36968 2.00000 -0.36968 0.00000 -0.01792 0.00000 -0.00130
]]></programlisting>
</refsection>
</refentry>
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