<!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>psb_precinit -- Initialize a preconditioner</TITLE> <META NAME="description" CONTENT="psb_precinit -- Initialize a preconditioner"> <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="node102.html"> <LINK REL="previous" HREF="node100.html"> <LINK REL="up" HREF="node100.html"> <LINK REL="next" HREF="node102.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html1450" HREF="node102.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html1446" HREF="node100.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html1440" HREF="node100.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html1448" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <BR> <B> Next:</B> <A NAME="tex2html1451" HREF="node102.html">psb_precbld Builds</A> <B> Up:</B> <A NAME="tex2html1447" HREF="node100.html">Preconditioner routines</A> <B> Previous:</B> <A NAME="tex2html1441" HREF="node100.html">Preconditioner routines</A> <B> <A NAME="tex2html1449" HREF="node1.html">Contents</A></B> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION000111000000000000000"> psb_precinit -- Initialize a preconditioner</A> </H2> <P> <PRE> call psb_precinit(prec, ptype, info) </PRE> <P> <DL> <DT><STRONG>Type:</STRONG></DT> <DD>Asynchronous. </DD> <DT><STRONG><B>On Entry</B></STRONG></DT> <DD> </DD> <DT><STRONG>ptype</STRONG></DT> <DD>the type of preconditioner. Scope: <B>global</B> <BR> Type: <B>required</B> <BR> Intent: <B>in</B>. <BR> Specified as: a character string, see usage notes. </DD> <DT><STRONG><B>On Exit</B></STRONG></DT> <DD><P> </DD> <DT><STRONG>prec</STRONG></DT> <DD>Scope: <B>local</B> <BR> Type: <B>required</B> <BR> Intent: <B>inout</B>. <BR> Specified as: a preconditioner data structure precdata<TT>psb_prec_type</TT>. </DD> <DT><STRONG>info</STRONG></DT> <DD>Scope: <B>global</B> <BR> Type: <B>required</B> <BR> Intent: <B>out</B>. <BR> Error code: if no error, 0 is returned. </DD> </DL> <FONT SIZE="+1"><B>Notes</B></FONT> Legal inputs to this subroutine are interpreted depending on the <IMG WIDTH="42" HEIGHT="30" ALIGN="MIDDLE" BORDER="0" SRC="img140.png" ALT="$ptype$"> string as follows<A NAME="tex2html28" HREF="footnode.html#foot6742"><SUP>3</SUP></A>: <DL> <DT><STRONG>NONE</STRONG></DT> <DD>No preconditioning, i.e. the preconditioner is just a copy operator. </DD> <DT><STRONG>DIAG</STRONG></DT> <DD>Diagonal scaling; each entry of the input vector is multiplied by the reciprocal of the sum of the absolute values of the coefficients in the corresponding row of matrix <IMG WIDTH="16" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" SRC="img1.png" ALT="$A$">; </DD> <DT><STRONG>BJAC</STRONG></DT> <DD>Precondition by a factorization of the block-diagonal of matrix <IMG WIDTH="16" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" SRC="img1.png" ALT="$A$">, where block boundaries are determined by the data allocation boundaries for each process; requires no communication. Only the incomplete factorization <IMG WIDTH="56" HEIGHT="32" ALIGN="MIDDLE" BORDER="0" SRC="img141.png" ALT="$ILU(0)$"> is currently implemented. </DD> </DL> <P> <BR><HR> </BODY> </HTML>