<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">

<!--Converted with LaTeX2HTML 2012 (1.2)
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>User-defined index mappings</TITLE>
<META NAME="description" CONTENT="User-defined index mappings">
<META NAME="keywords" CONTENT="userhtml">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">

<META NAME="Generator" CONTENT="LaTeX2HTML v2012">
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">

<LINK REL="STYLESHEET" HREF="userhtml.css">

<LINK REL="previous" HREF="node6.html">
<LINK REL="up" HREF="node6.html">
<LINK REL="next" HREF="node8.html">
</HEAD>

<BODY >
<!--Navigation Panel-->
<A NAME="tex2html271"
  HREF="node8.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> 
<A NAME="tex2html267"
  HREF="node6.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> 
<A NAME="tex2html263"
  HREF="node6.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> 
<A NAME="tex2html269"
  HREF="node1.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A>  
<BR>
<B> Next:</B> <A NAME="tex2html272"
  HREF="node8.html">Programming model</A>
<B> Up:</B> <A NAME="tex2html268"
  HREF="node6.html">Application structure</A>
<B> Previous:</B> <A NAME="tex2html264"
  HREF="node6.html">Application structure</A>
 &nbsp; <B>  <A NAME="tex2html270"
  HREF="node1.html">Contents</A></B> 
<BR>
<BR>
<!--End of Navigation Panel-->

<H3><A NAME="SECTION00033100000000000000"></A>
<A NAME="sec:usermaps"></A>
<BR>
User-defined index mappings
</H3>
PSBLAS supports user-defined global to local index mappings, subject
to the constraints outlined in sec.&nbsp;<A HREF="node6.html#sec:appstruct">2.3</A>: 

<OL>
<LI>The set of indices owned locally must be mapped to the set
  <!-- MATH
 $1\dots n_{\hbox{row}_i}$
 -->
<IMG
 WIDTH="77" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img17.png"
 ALT="$1\dots n_{\hbox{row}_i}$">;
</LI>
<LI>The set of halo points must be mapped to the set
  <!-- MATH
 $n_{\hbox{row}_i}+1\dots n_{\hbox{col}_i}$
 -->
<IMG
 WIDTH="130" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img18.png"
 ALT="$n_{\hbox{row}_i}+1\dots n_{\hbox{col}_i}$">;
</LI>
</OL>
but otherwise the mapping is arbitrary. The user application is
responsible to ensure consistency of this mapping; some errors may be
caught by the library, but this is not guaranteed. 
The application structure to
support this usage is as follows:

<OL>
<LI>Initialize index space with
  <code>psb_cdall(ictx,desc,info,vl=vl,lidx=lidx)</code> passing the vectors 
  <code>vl(:)</code> containing the set of global indices owned by the
  current process and   <code>lidx(:)</code> containing the corresponding
  local indices;
</LI>
<LI>Add the halo points <code>ja(:)</code> and their associated local
  indices <code>lidx(:)</code>  with a(some) call(s) to
  <code>psb_cdins(nz,ja,desc,info,lidx=lidx)</code>; 
</LI>
<LI>Assemble the descriptor with <code>psb_cdasb</code>;
</LI>
<LI>Build the sparse matrices and vectors, optionally making use in
  <code>psb_spins</code> and <code>psb_geins</code> of the <code>local</code> argument
  specifying that the indices in <code>ia</code>, <code>ja</code> and <code>irw</code>,
  respectively, are already local indices. 
</LI>
</OL>

<P>
<BR><HR>

</BODY>
</HTML>