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<?xml version="1.0" encoding="UTF-8"?>
<!--
 * Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
 * Copyright (C) INRIA - F.D
 * Revised July 2011, S. Steer, 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_V2.1-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" xmlns:scilab="http://www.scilab.org" xml:lang="en" xml:id="pfss">
    <refnamediv>
        <refname>pfss</refname>
        <refpurpose>partial fraction decomposition</refpurpose>
    </refnamediv>
    <refsynopsisdiv>
        <title>Calling Sequence</title>
        <synopsis>elts=pfss(Sl)
            elts=pfss(Sl,rmax)
            elts=pfss(Sl,cord)
            elts=pfss(Sl,rmax,cord)
        </synopsis>
    </refsynopsisdiv>
    <refsection>
        <title>Arguments</title>
        <variablelist>
            <varlistentry>
                <term>Sl</term>
                <listitem>
                    <para>
                        A linear dynamical system in state-space or transfer
                        function representation (see <link linkend="syslin">syslin</link>).
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>rmax</term>
                <listitem>
                    <para>
                        A real number controlling the conditioning of block
                        diagonalization (see  <link linkend="bdiag">bdiag</link>).
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>cord</term>
                <listitem>
                    <para>
                        A character string with possible values <literal>'c'</literal>
                        or <literal>'d'</literal>.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsection>
    <refsection>
        <title>Description</title>
        <para>
            Partial fraction decomposition of the linear system <literal>Sl</literal>.
        </para>
        <para>
            <literal>elts</literal> is the list of linear systems which add up to <literal>Sl</literal>
            i.e. <literal>elts=list(S1,S2,S3,...,Sn)</literal> with:
        </para>
        <para>
            <literal>Sl = S1 + S2 +... +Sn</literal>.
        </para>
        <para>
            Each <literal>Si</literal> contains some poles of <literal/>
            Saccording to the 
            block-diagonalization of the <literal>A</literal> matrix of <literal>S</literal>.
        </para>
        <para>
            For non proper systems the polynomial part of <literal>Sl</literal> is put
            in the last entry of <literal>elts</literal>.
        </para>
        <para>
            If <literal>Sl</literal> is given in transfer form, it is first
            converted into state-space by <link linkend="tf2ss">tf2ss</link>
            and each subsystem <literal>Si</literal> is then converted in
            transfer form by <link linkend="ss2tf">ss2tf</link>.
        </para>
        <para>
            The A matrix is of the state-space is put into block diagonal form
            by function <link linkend="bdiag">bdiag</link>. The optional parameter
            <literal>rmax</literal> is sent to <literal>bdiag</literal>, 
            <literal>rmax</literal> should be set to a large number to enforce
            block-diagonalization.
        </para>
        <para>
            If the optional flag <literal>cord='c'</literal> is given the elements in <literal>elts</literal>
            are sorted according to the real part (resp. magnitude if <literal>cord='d'</literal>)
            of the eigenvalues of A matrices.
        </para>
    </refsection>
    <refsection>
        <title>Examples</title>
        <programlisting role="example"><![CDATA[ 
    W=ssrand(1,1,6);
    elts=pfss(W); 
    W1=0;for k=1:size(elts), W1=W1+ss2tf(elts(k));end
    clean(ss2tf(W)-W1)
    ]]></programlisting>
        <programlisting role="example"><![CDATA[ 
    num=22801+4406.18*s+382.37*s^2+21.02*s^3+s^4;
    den=22952.25+4117.77*s+490.63*s^2+33.06*s^3+s^4
    h2=syslin('c',num/den);
    ]]></programlisting>
    </refsection>
    <refsection role="see also">
        <title>See Also</title>
        <simplelist type="inline">
            <member>
                <link linkend="pbig">pbig</link>
            </member>
            <member>
                <link linkend="bdiag">bdiag</link>
            </member>
            <member>
                <link linkend="coffg">coffg</link>
            </member>
            <member>
                <link linkend="dtsi">dtsi</link>
            </member>
        </simplelist>
    </refsection>
</refentry>