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<?xml version="1.0" encoding="UTF-8"?>
<!--
* Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
* Copyright (C) 2006-2008 - INRIA
*
* This file must be used under the terms of the CeCILL.
* This source file is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at
* http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
*
-->
<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" version="5.0-subset Scilab" xml:lang="en" xml:id="clean">
<info>
<pubdate>$LastChangedDate$</pubdate>
</info>
<refnamediv>
<refname>clean</refname>
<refpurpose> cleans matrices (round to zero small entries) </refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>B=clean(A [,epsa [,epsr]])</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term>A</term>
<listitem>
<para>a numerical matrix (scalar, polynomial, sparse...)</para>
</listitem>
</varlistentry>
<varlistentry>
<term>epsa,epsr</term>
<listitem>
<para>real numbers. Cleaning tolerances (default values resp. 1.d-10 and 1.d-10)</para>
</listitem>
</varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para>
This function eliminates (i.e. set to zero) all the coefficients
with absolute value < <literal>epsa</literal> or relative value < <literal>epsr</literal>
(relative means relative w.r.t. 1-norm of coefficients)
in a polynomial (possibly matrix polynomial or rational
matrix).</para>
<para>
Default values are <literal>epsa=1.d-10</literal> and <literal>epsr=1.d-10;</literal></para>
<para>
For a constant (non polynomial) matrix <literal>clean(A,epsa)</literal> sets to zero all
entries of <literal>A</literal> smaller than <literal>epsa</literal>.</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
x=poly(0,'x');
w=[x,1,2+x;3+x,2-x,x^2;1,2,3+x]/3;
w*inv(w)
clean(w*inv(w))
]]></programlisting>
</refsection>
</refentry>
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