text: <?xml version="1.0" encoding="UTF-8"?>
  <!--
   * Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
   * Copyright (C) 2008 - INRIA
   * Copyright (C) 2012 - 2016 - Scilab Enterprises
   *
   * This file is hereby licensed under the terms of the GNU GPL v2.0,
   * pursuant to article 5.3.4 of the CeCILL v.2.1.
   * This file was originally licensed under the terms of the CeCILL v2.1,
   * and continues to be available under such terms.
   * For more information, see the COPYING file which you should have received
   * along with this program.
   *
   -->
  <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="ja" xml:id="rcond">
      <refnamediv>
          <refname>rcond</refname>
          <refpurpose>条件数の逆数</refpurpose>
      </refnamediv>
      <refsynopsisdiv>
          <title>呼び出し手順</title>
          <synopsis>r = rcond(X)</synopsis>
      </refsynopsisdiv>
      <refsection>
          <title>引数</title>
          <variablelist>
              <varlistentry>
                  <term>X</term>
                  <listitem>
                      <para>実数または複素数の正方行列</para>
                  </listitem>
              </varlistentry>
              <varlistentry>
                  <term>r</term>
                  <listitem>
                      <para>正の実数</para>
                  </listitem>
              </varlistentry>
          </variablelist>
      </refsection>
      <refsection>
          <title>説明</title>
          <para>
              <literal>rcond(X)</literal> は,1-ノルムにおける
              <literal>X</literal>の条件の逆数の推定値です.
          </para>
          <para>
              <literal>X</literal>が健全な場合,
              <literal>rcond(X)</literal> は 1 に近くなります.
              そうでない場合, <literal>rcond(X)</literal> は 0に近くなります.
          </para>
          <para>
              <note>
              <literal>rcond</literal>による1-ノルム逆条件数の推定は,
              <literal>cond</literal>による2-ノルム条件数の計算よりはるかに高速です.
              トレードオフとして,<literal>rcond</literal> は若干信頼性が低下する可能性があります.
              </note>
          </para>
          <para>
              Xの1-ノルムを Lapack/DLANGEで計算, そのLU分解をLapack/DGETRFで計算,
              最後に条件をLapack/DGECONで推定します.
          </para>
          <para>
            <literal>rcond([])</literal> yields <literal>%inf</literal>.
          </para>
  
      </refsection>
      <refsection>
          <title>例</title>
          <programlisting role="example"><![CDATA[
  A = diag([1:10]);
  rcond(A)
  A(1,1) = 0.000001;
  rcond(A)
   ]]></programlisting>
      <para>比較ベンチマーク</para>
      <programlisting role="example"><![CDATA[
      A = ones(1000, 1000);
      timer(); cond(A);    timer()
      timer(); 1/rcond(A); timer()
   ]]></programlisting>
      </refsection>
      <refsection role="see also">
          <title>参照</title>
          <simplelist type="inline">
              <member>
                  <link linkend="svd">svd</link>
              </member>
              <member>
                  <link linkend="cond">cond</link>
              </member>
              <member>
                  <link linkend="inv">inv</link>
              </member>
          </simplelist>
      </refsection>
      <refsection role="history">
          <title>履歴</title>
          <revhistory>
              <revision>
                  <revnumber>6.0.2</revnumber>
                  <revdescription>
                      rcond([]) now yields %inf = 1/cond([]) instead of [].
                  </revdescription>
              </revision>
          </revhistory>
      </refsection>
  </refentry>