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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:ns5="http://www.w3.org/1999/xhtml" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" xmlns:scilab="http://www.scilab.org" xml:id="hess" xml:lang="pt">
    <refnamediv>
        <refname>hess</refname>
        <refpurpose>forma de Hessenberg</refpurpose>
    </refnamediv>
    <refsynopsisdiv>
        <title> Seqüência de Chamamento </title>
        <synopsis>H = hess(A)
            [U,H] = hess(A)
        </synopsis>
    </refsynopsisdiv>
    <refsection>
        <title>Parâmetros</title>
        <variablelist>
            <varlistentry>
                <term>A</term>
                <listitem>
                    <para>matriz quadrada de reais ou complexos </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>H</term>
                <listitem>
                    <para>matriz quadrada de reais ou complexos </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>U</term>
                <listitem>
                    <para>matriz quadrada ortogonal ou unitária</para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsection>
    <refsection>
        <title>Descrição</title>
        <para>
            <literal>[U,H] = hess(A)</literal> produz uma matriz unitária
            <literal>U</literal> e uma matriz de Hessenberg <literal>H</literal> tais
            que <literal>A = U*H*U'</literal> e <literal>U'*U</literal> = Identidade.
            Por si só, <literal>hess(A) </literal>retorna <literal>H</literal>.
        </para>
        <para>A forma de Hessenberg de uma matriz é zero abaixo da primeira
            subdiagonal. Se a matriz é simetrica ou Hermitiana, a forma é
            tridiagonal.
        </para>
    </refsection>
    <refsection>
        <title>Referências</title>
        <para>A função hess é baseada nas rotinas Lapack DGEHRD, DORGHR para
            matrizes de e ZGEHRD, ZORGHR para matrizes de complexos.
        </para>
    </refsection>
    <refsection>
        <title>Exemplos</title>
        <programlisting role="example"><![CDATA[
A=rand(3,3);[U,H]=hess(A);
and( abs(U*H*U'-A)<1.d-10 )
 ]]></programlisting>
    </refsection>
    <refsection>
        <title> Ver Também </title>
        <simplelist type="inline">
            <member>
                <link linkend="qr">qr</link>
            </member>
            <member>
                <link linkend="contr">contr</link>
            </member>
            <member>
                <link linkend="schur">schur</link>
            </member>
        </simplelist>
    </refsection>
    <refsection>
        <title/>
        <para/>
    </refsection>
</refentry>
