<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 2008 (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>Preconditioner data structure</TITLE> <META NAME="description" CONTENT="Preconditioner data structure"> <META NAME="keywords" CONTENT="userhtml"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META NAME="Generator" CONTENT="LaTeX2HTML v2008"> <META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"> <LINK REL="STYLESHEET" HREF="userhtml.css"> <LINK REL="next" HREF="node16.html"> <LINK REL="previous" HREF="node13.html"> <LINK REL="up" HREF="node8.html"> <LINK REL="next" HREF="node16.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html357" HREF="node16.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html353" HREF="node8.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html347" HREF="node14.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html355" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <BR> <B> Next:</B> <A NAME="tex2html358" HREF="node16.html">Data structure query routines</A> <B> Up:</B> <A NAME="tex2html354" HREF="node8.html">Data Structures</A> <B> Previous:</B> <A NAME="tex2html348" HREF="node14.html">Named Constants</A> <B> <A NAME="tex2html356" HREF="node1.html">Contents</A></B> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION00044000000000000000"></A> <A NAME="sec:prec"></A> <BR> Preconditioner data structure </H2> Our base library offers support for simple well known preconditioners like Diagonal Scaling or Block Jacobi with incomplete factorization ILU(0). <P> A preconditioner is held in the precdata<TT> psb_prec_type</TT> data structure reported in figure <A HREF="#fig:prectype">6</A>. The <code>psb_prec_type</code> data type may contain a simple preconditioning matrix with the associated communication descriptor.The values contained in the <code>iprcparm</code> and <code>rprcparm</code> define tha type of preconditioner along with all the parameters related to it; thus, <code>iprcparm</code> and <code>rprcparm</code> define how the other records have to be interpreted. This data structure is the basis of more complex preconditioning strategies, which are the subject of further research. <DIV ALIGN="CENTER"><A NAME="fig:prectype"></A><A NAME="674"></A> <TABLE> <CAPTION ALIGN="BOTTOM"><STRONG>Figure 6:</STRONG> The PSBLAS defined data type that contains a preconditioner.</CAPTION> <TR><TD><FONT SIZE="-1"> <BR> <BR> </FONT> <DIV ALIGN="CENTER"><FONT SIZE="-1"><!-- MATH $\fbox{\TheSbox}$ --> <IMG WIDTH="535" HEIGHT="218" ALIGN="MIDDLE" BORDER="0" SRC="img20.png" ALT="\fbox{\TheSbox}"></FONT></DIV><FONT SIZE="-1"> </FONT></TD></TR> </TABLE> </DIV> <P> <BR><HR> </BODY> </HTML>