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<?xml version="1.0" encoding="UTF-8"?>
<!--
* Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
* Copyright (C) XXXX-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="sparse">
<info>
<pubdate>$LastChangedDate$</pubdate>
</info>
<refnamediv>
<refname>sparse</refname>
<refpurpose> sparse matrix definition</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>sp=sparse(X)
sp=sparse(ij,v [,mn])</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term>X</term>
<listitem>
<para>real or complex full (or sparse) matrix</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ij</term>
<listitem>
<para>two columns integer matrix (indices of non-zeros entries)</para>
</listitem>
</varlistentry>
<varlistentry>
<term>v</term>
<listitem>
<para>vector</para>
</listitem>
</varlistentry>
<varlistentry>
<term>mn</term>
<listitem>
<para>integer vector with two entries (row-dimension, column-dimension)</para>
</listitem>
</varlistentry>
<varlistentry>
<term>sp</term>
<listitem>
<para>sparse matrix</para>
</listitem>
</varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<para><literal>sparse</literal> is used to build a sparse matrix. Only non-zero entries
are stored.</para>
<para><literal>sp = sparse(X)</literal> converts a full matrix to sparse form by
squeezing out any zero elements. (If <literal>X</literal> is already sparse
<literal>sp</literal> is <literal>X</literal>).</para>
<para><literal>sp=sparse(ij,v [,mn])</literal> builds an <literal>mn(1)</literal>-by-<literal>mn(2)</literal>
sparse matrix with <literal>sp(ij(k,1),ij(k,2))=v(k)</literal>.
<literal>ij</literal> and <literal>v</literal> must have the same column dimension.
If optional <literal>mn</literal> parameter is not given the <literal>sp</literal>
matrix dimensions are the max value of <literal>ij(:,1)</literal> and <literal>ij(:,2)</literal>
respectively.</para>
<para>
Operations (concatenation, addition, etc,) with sparse matrices are
made using the same syntax as for full matrices.</para>
<para>
Elementary functions are also available (<literal>abs,maxi,sum,diag,...</literal>)
for sparse matrices.</para>
<para>
Mixed operations (full-sparse) are allowed. Results are full or sparse
depending on the operations.</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
sp=sparse([1,2;4,5;3,10],[1,2,3])
size(sp)
x=rand(2,2);abs(x)-full(abs(sparse(x)))
]]></programlisting>
</refsection>
<refsection>
<title>See Also</title>
<simplelist type="inline">
<member>
<link linkend="full">full</link>
</member>
<member>
<link linkend="spget">spget</link>
</member>
<member>
<link linkend="sprand">sprand</link>
</member>
<member>
<link linkend="speye">speye</link>
</member>
<member>
<link linkend="lufact">lufact</link>
</member>
</simplelist>
</refsection>
</refentry>
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