<?xml version="1.0" encoding="UTF-8"?>
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<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="arhnk">
    <refnamediv>
        <refname>arhnk</refname>
        <refpurpose>Hankel norm approximant</refpurpose>
    </refnamediv>
    <refsynopsisdiv>
        <title>Syntax</title>
        <synopsis>
            slm = arhnk(sl, ord)
            slm = arhnk(sl, ord, tol)
        </synopsis>
    </refsynopsisdiv>
    <refsection>
        <title>Arguments</title>
        <variablelist>
            <varlistentry>
                <term>sl</term>
                <listitem>
                    <para>
                        linear system (<literal>syslin</literal> list)
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>ord</term>
                <listitem>
                    <para>integer, order of the approximant</para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>tol</term>
                <listitem>
                    <para>
                        threshold for rank determination in <literal>equil1</literal>
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsection>
    <refsection>
        <title>Description</title>
        <para>
            computes <literal>slm</literal>, the optimal Hankel norm approximant of the
            stable continuous-time linear system <literal>sl</literal> with matrices <literal>[A,B,C,D]</literal>.
        </para>
    </refsection>
    <refsection>
        <title>Examples</title>
        <programlisting role="example"><![CDATA[
A=diag([-1,-2,-3,-4,-5]);B=rand(5,1);C=rand(1,5);
sl=syslin('c',A,B,C);
slapprox=arhnk(sl,2);
[nk,W]=hankelsv(sl);nk
[nkred,Wred]=hankelsv(slapprox);nkred
 ]]></programlisting>
    </refsection>
    <refsection role="see also">
        <title>See also</title>
        <simplelist type="inline">
            <member>
                <link linkend="equil">equil</link>
            </member>
            <member>
                <link linkend="equil1">equil1</link>
            </member>
            <member>
                <link linkend="hankelsv">hankelsv</link>
            </member>
        </simplelist>
    </refsection>
</refentry>
