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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from fwht.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="fwht" 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>fwht</refname>
<refpurpose>Compute the Walsh-Hadamard transform of x using the Fast Walsh-Hadamard Transform (FWHT) algorithm</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>
fwht (x)
fwht (x, n)
fwht (x, n, order)
</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry><term>x:</term>
<listitem><para> real or complex valued scalar or vector</para></listitem></varlistentry>
<varlistentry><term>n:</term>
<listitem><para> x is truncated or extended to have length n</para></listitem></varlistentry>
<varlistentry><term>order:</term>
<listitem><para> Specification of order in which coefficients should be arranged</para></listitem></varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para>
Compute the Walsh-Hadamard transform of x using the Fast Walsh-Hadamard Transform (FWHT) algorithm. If the input is a matrix, the FWHT is calculated along the columns of x.
</para>
<para>
The number of elements of x must be a power of 2; if not, the input will be extended and filled with zeros. If a second argument is given, the input is truncated or extended to have length n.
</para>
<para>
The third argument specifies the order in which the returned Walsh-Hadamard transform coefficients should be arranged. The order may be any of the following strings:
</para>
<para>
"sequency"
The coefficients are returned in sequency order. This is the default if order is not given.
</para>
<para>
"hadamard"
The coefficients are returned in Hadamard order.
</para>
<para>
"dyadic"
The coefficients are returned in Gray code order.
</para>
</refsection>
</refentry>
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