<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<!--Converted with LaTeX2HTML 2002-2-1 (1.71)
original version by: Nikos Drakos, CBLU, University of Leeds
* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan
* with significant contributions from:
Jens Lippmann, Marek Rouchal, Martin Wilck and others -->
<HTML>
<HEAD>
<TITLE>Subroutine mld_precaply</TITLE>
<META NAME="description" CONTENT="Subroutine mld_precaply">
<META NAME="keywords" CONTENT="userhtml">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">
<META NAME="Generator" CONTENT="LaTeX2HTML v2002-2-1">
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
<LINK REL="STYLESHEET" HREF="userhtml.css">
<LINK REL="next" HREF="node21.html">
<LINK REL="previous" HREF="node19.html">
<LINK REL="up" HREF="node16.html">
<LINK REL="next" HREF="node21.html">
</HEAD>
<BODY >
<!--Navigation Panel-->
<A NAME="tex2html308"
HREF="node21.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next"
SRC="file:/usr/share/latex2html/icons/next.png"></A>
<A NAME="tex2html304"
HREF="node16.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up"
SRC="file:/usr/share/latex2html/icons/up.png"></A>
<A NAME="tex2html298"
HREF="node19.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous"
SRC="file:/usr/share/latex2html/icons/prev.png"></A>
<A NAME="tex2html306"
HREF="node2.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents"
SRC="file:/usr/share/latex2html/icons/contents.png"></A>
<BR>
<B> Next:</B> <A NAME="tex2html309"
HREF="node21.html">Subroutine mld_precfree</A>
<B> Up:</B> <A NAME="tex2html305"
HREF="node16.html">User Interface</A>
<B> Previous:</B> <A NAME="tex2html299"
HREF="node19.html">Subroutine mld_precbld</A>
<B> <A NAME="tex2html307"
HREF="node2.html">Contents</A></B>
<BR>
<BR>
<!--End of Navigation Panel-->
<H2><A NAME="SECTION00084000000000000000"></A><A NAME="sec:precaply"></A>
<BR>
Subroutine mld_precaply
</H2>
<P>
<DIV ALIGN="CENTER">
<code>mld_precaply(p,x,y,desc_a,info)</code>
<BR><code>mld_precaply(p,x,y,desc_a,info,trans,work)</code>
<BR>
</DIV>
<P>
This routine computes <!-- MATH
$y = op(M^{-1})\, x$
-->
<IMG
WIDTH="117" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
SRC="img96.png"
ALT="$y = op(M^{-1}) x$">, where <IMG
WIDTH="23" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
SRC="img59.png"
ALT="$M$"> is a previously built
preconditioner, stored into <code>p</code>, and <IMG
WIDTH="22" HEIGHT="31" ALIGN="MIDDLE" BORDER="0"
SRC="img97.png"
ALT="$op$">
denotes the preconditioner itself or its transpose, according to
the value of <code>trans</code>.
Note that, when MLD2P4 is used with a Krylov solver from PSBLAS,
<code>mld_precaply</code> is called within the PSBLAS routine <code>psb_krylov</code>
and hence it is completely transparent to the user.
<P>
<FONT SIZE="+1"><B>Arguments</B></FONT>
<P>
<TABLE CELLPADDING=3>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34><code>p</code></TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340><code>type(mld_</code><I>x</I><code>prec_type), intent(inout)</code>.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34> </TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340>The preconditioner data structure, containing the local part of <IMG
WIDTH="23" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
SRC="img59.png"
ALT="$M$">.
Note that <I>x</I> must be chosen according
to the real/complex, single/double precision version of MLD2P4 under use.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34><code>x</code></TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340><I>type</I><code>(</code><I>kind_parameter</I><code>), dimension(:), intent(in)</code>.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34> </TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340>The local part of the vector <IMG
WIDTH="14" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
SRC="img98.png"
ALT="$x$">. Note that <I>type</I> and
<I>kind_parameter</I> must be chosen according
to the real/complex, single/double precision version of MLD2P4 under use.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34><code>y</code></TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340><I>type</I><code>(</code><I>kind_parameter</I><code>), dimension(:), intent(out)</code>.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34> </TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340>The local part of the vector <IMG
WIDTH="14" HEIGHT="31" ALIGN="MIDDLE" BORDER="0"
SRC="img99.png"
ALT="$y$">. Note that <I>type</I> and
<I>kind_parameter</I> must be chosen according
to the real/complex, single/double precision version of MLD2P4 under use.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34><code>desc_a</code></TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340><code>type(psb_desc_type), intent(in)</code>.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34> </TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340>The communication descriptor associated to the matrix to be
preconditioned.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34><code>info</code></TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340><code>integer, intent(out)</code>.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34> </TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340>Error code. If no error, 0 is returned. See Section <A HREF="node23.html#sec:errors">7</A> for details.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34><code>trans</code></TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340><code>character(len=1), optional, intent(in).</code></TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34> </TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340>If <code>trans</code> = <code>'N','n'</code> then <!-- MATH
$op(M^{-1}) = M^{-1}$
-->
<IMG
WIDTH="132" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
SRC="img100.png"
ALT="$op(M^{-1}) = M^{-1}$">;
if <code>trans</code> = <code>'T','t'</code> then <!-- MATH
$op(M^{-1}) = M^{-T}$
-->
<IMG
WIDTH="135" HEIGHT="40" ALIGN="MIDDLE" BORDER="0"
SRC="img101.png"
ALT="$op(M^{-1}) = M^{-T}$">
(transpose of <IMG
WIDTH="48" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
SRC="img102.png"
ALT="$M^{-1})$">; if <code>trans</code> = <code>'C','c'</code> then <!-- MATH
$op(M^{-1}) = M^{-C}$
-->
<IMG
WIDTH="136" HEIGHT="40" ALIGN="MIDDLE" BORDER="0"
SRC="img103.png"
ALT="$op(M^{-1}) = M^{-C}$">
(conjugate transpose of <IMG
WIDTH="48" HEIGHT="39" ALIGN="MIDDLE" BORDER="0"
SRC="img102.png"
ALT="$M^{-1})$">.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34><code>work</code></TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340><I>type</I><code>(</code><I>kind_parameter</I><code>), dimension(:), optional, target</code>.</TD>
</TR>
<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=34> </TD>
<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=340>Workspace. Its size should be at
least <code>4 * psb_cd_get_local_</code> <code>cols(desc_a)</code> (see the PSBLAS User's Guide).
Note that <I>type</I> and <I>kind_parameter</I> must be chosen according
to the real/complex, single/double precision version of MLD2P4 under use.</TD>
</TR>
</TABLE>
<P>
<P>
<HR>
<!--Navigation Panel-->
<A NAME="tex2html308"
HREF="node21.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next"
SRC="file:/usr/share/latex2html/icons/next.png"></A>
<A NAME="tex2html304"
HREF="node16.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up"
SRC="file:/usr/share/latex2html/icons/up.png"></A>
<A NAME="tex2html298"
HREF="node19.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous"
SRC="file:/usr/share/latex2html/icons/prev.png"></A>
<A NAME="tex2html306"
HREF="node2.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents"
SRC="file:/usr/share/latex2html/icons/contents.png"></A>
<BR>
<B> Next:</B> <A NAME="tex2html309"
HREF="node21.html">Subroutine mld_precfree</A>
<B> Up:</B> <A NAME="tex2html305"
HREF="node16.html">User Interface</A>
<B> Previous:</B> <A NAME="tex2html299"
HREF="node19.html">Subroutine mld_precbld</A>
<B> <A NAME="tex2html307"
HREF="node2.html">Contents</A></B>
<!--End of Navigation Panel-->
</BODY>
</HTML>