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<TITLE>HPL_pdmxswp HPL 2.0 Library Functions September 10, 2008</TITLE> |
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ALINK = "#ffff00"> |
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<H1>Name</H1> |
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<B>HPL_pdmxswp</B> swaps and broacast the pivot row. |
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<H1>Synopsis</H1> |
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<CODE>#include "hpl.h"</CODE><BR><BR> |
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<CODE>void</CODE> |
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<CODE>HPL_pdmxswp(</CODE> |
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<CODE>HPL_T_panel *</CODE> |
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<CODE>PANEL</CODE>, |
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<CODE>const int</CODE> |
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<CODE>M</CODE>, |
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<CODE>const int</CODE> |
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<CODE>II</CODE>, |
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<CODE>const int</CODE> |
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<CODE>JJ</CODE>, |
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<CODE>double *</CODE> |
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<CODE>WORK</CODE> |
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<CODE>);</CODE> |
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<H1>Description</H1> |
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<B>HPL_pdmxswp</B> |
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swaps and broadcasts the absolute value max row using |
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bi-directional exchange. The buffer is partially set by HPL_dlocmax. |
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Bi-directional exchange is used to perform the swap::broadcast |
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operations at once for one column in the panel. This results in a |
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lower number of slightly larger messages than usual. On P processes |
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and assuming bi-directional links, the running time of this function |
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can be approximated by |
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log_2( P ) * ( lat + ( 2 * N0 + 4 ) / bdwth ) |
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where lat and bdwth are the latency and bandwidth of the network for |
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double precision real elements. Communication only occurs in one |
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process column. Mono-directional links will cause the communication |
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cost to double. |
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<H1>Arguments</H1> |
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<PRE>
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PANEL (local input/output) HPL_T_panel * |
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On entry, PANEL points to the data structure containing the |
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panel information. |
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</PRE>
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<PRE>
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M (local input) const int |
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On entry, M specifies the local number of rows of the matrix |
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column on which this function operates. |
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</PRE>
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<PRE>
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II (local input) const int |
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On entry, II specifies the row offset where the column to be |
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operated on starts with respect to the panel. |
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</PRE>
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<PRE>
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JJ (local input) const int |
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On entry, JJ specifies the column offset where the column to |
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be operated on starts with respect to the panel. |
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</PRE>
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<PRE>
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WORK (local workspace) double * |
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On entry, WORK is a workarray of size at least 2 * (4+2*N0). |
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It is assumed that HPL_dlocmax was called prior to this |
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routine to initialize the first four entries of this array. |
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On exit, the N0 length max row is stored in WORK[4:4+N0-1]; |
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Note that this is also the JJth row (or column) of L1. The |
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remaining part is used as a temporary array. |
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</PRE>
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<H1>See Also</H1> |
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<A HREF="HPL_dlocmax.html">HPL_dlocmax</A>, |
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<A HREF="HPL_dlocswpN.html">HPL_dlocswpN</A>, |
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<A HREF="HPL_dlocswpT.html">HPL_dlocswpT</A>, |
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<A HREF="HPL_pdpancrN.html">HPL_pdpancrN</A>, |
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<A HREF="HPL_pdpancrT.html">HPL_pdpancrT</A>, |
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<A HREF="HPL_pdpanllN.html">HPL_pdpanllN</A>, |
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<A HREF="HPL_pdpanllT.html">HPL_pdpanllT</A>, |
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<A HREF="HPL_pdpanrlN.html">HPL_pdpanrlN</A>, |
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<A HREF="HPL_pdpanrlT.html">HPL_pdpanrlT</A>, |
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<A HREF="HPL_pdrpancrN.html">HPL_pdrpancrN</A>, |
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<A HREF="HPL_pdrpancrT.html">HPL_pdrpancrT</A>, |
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<A HREF="HPL_pdrpanllN.html">HPL_pdrpanllN</A>, |
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<A HREF="HPL_pdrpanllT.html">HPL_pdrpanllT</A>, |
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<A HREF="HPL_pdrpanrlN.html">HPL_pdrpanrlN</A>, |
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<A HREF="HPL_pdrpanrlT.html">HPL_pdrpanrlT</A>, |
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<A HREF="HPL_pdfact.html">HPL_pdfact</A>. |
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</BODY>
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