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<H2><A NAME="SECTION00063000000000000000">
psb_gather -- Gather Global Dense Matrix</A>
</H2>

<P>
These subroutines collect the portions of global dense matrix
distributed over all process into one single array stored on one
process.

<P>
<BR><P></P>
<DIV ALIGN="CENTER">
<!-- MATH
 \begin{displaymath}
glob\_x \leftarrow collect(loc\_x_i)
\end{displaymath}
 -->

<IMG
 WIDTH="163" HEIGHT="28" BORDER="0"
 SRC="img68.png"
 ALT="\begin{displaymath}glob\_x \leftarrow collect(loc\_x_i) \end{displaymath}">
</DIV>
<BR CLEAR="ALL">
<P></P>
where:
<DL>
<DT><STRONG><IMG
 WIDTH="46" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img69.png"
 ALT="$glob\_x$"></STRONG></DT>
<DD>is the global submatrix <!-- MATH
 $glob\_x_{1:m,1:n}$
 -->
<IMG
 WIDTH="91" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img70.png"
 ALT="$glob\_x_{1:m,1:n}$">
</DD>
<DT><STRONG><IMG
 WIDTH="43" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img71.png"
 ALT="$loc\_x_i$"></STRONG></DT>
<DD>is the local portion of global dense matrix on
process <IMG
 WIDTH="9" HEIGHT="17" ALIGN="BOTTOM" BORDER="0"
 SRC="img4.png"
 ALT="$i$">.
</DD>
<DT><STRONG><IMG
 WIDTH="49" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
 SRC="img72.png"
 ALT="$collect$"></STRONG></DT>
<DD>is the collect function.
</DD>
</DL>

<P>
<BR><P></P>
<DIV ALIGN="CENTER"><A NAME="2954"></A>
<TABLE>
<CAPTION><STRONG>Table 16:</STRONG>
Data types</CAPTION>
<TR><TD>
<DIV ALIGN="CENTER">
<TABLE CELLPADDING=3 BORDER="1" ALIGN="CENTER">
<TR><TD ALIGN="LEFT"><IMG
 WIDTH="33" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img73.png"
 ALT="$x_i, y$"></TD>
<TD ALIGN="LEFT"><B>Subroutine</B></TD>
</TR>
<TR><TD ALIGN="LEFT">Integer</TD>
<TD ALIGN="LEFT">psb_gather</TD>
</TR>
<TR><TD ALIGN="LEFT">Short Precision Real</TD>
<TD ALIGN="LEFT">psb_gather</TD>
</TR>
<TR><TD ALIGN="LEFT">Long Precision Real</TD>
<TD ALIGN="LEFT">psb_gather</TD>
</TR>
<TR><TD ALIGN="LEFT">Short Precision Complex</TD>
<TD ALIGN="LEFT">psb_gather</TD>
</TR>
<TR><TD ALIGN="LEFT">Long Precision Complex</TD>
<TD ALIGN="LEFT">psb_gather</TD>
</TR>
</TABLE>
</DIV>
</TD></TR>
</TABLE>
</DIV><P></P>
<BR>

<P>
<PRE>
call psb_gather(glob_x, loc_x, desc_a, info, root)
call psb_gather(glob_x, loc_x, desc_a, info, root)
</PRE>

<P>
<DL>
<DT><STRONG>Type:</STRONG></DT>
<DD>Synchronous.
</DD>
<DT><STRONG><B>On Entry</B></STRONG></DT>
<DD>
</DD>
<DT><STRONG>loc_x</STRONG></DT>
<DD>the local portion of global dense matrix
<IMG
 WIDTH="46" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img69.png"
 ALT="$glob\_x$">. 
<BR>
Scope: <B>local</B> 
<BR>
Type: <B>required</B>
<BR>
Intent: <B>in</B>.
<BR>
Specified as:  a rank one or two array or an object of type vdata<TT>psb_T_vect_type</TT> 
indicated in Table&nbsp;<A HREF="#tab:gather">16</A>.
</DD>
<DT><STRONG>desc_a</STRONG></DT>
<DD>contains data structures for communications.
<BR>
Scope: <B>local</B> 
<BR>
Type: <B>required</B>
<BR>
Intent: <B>in</B>.
<BR>
Specified as: a structured data of type descdata<TT>psb_desc_type</TT>.
</DD>
<DT><STRONG>root</STRONG></DT>
<DD>The process that holds the global copy. If <IMG
 WIDTH="75" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img74.png"
 ALT="$root=-1$"> all
  the processes will have a copy of the global vector.
<BR>
Scope: <B>global</B> 
<BR>
Type: <B>optional</B>
<BR>
Intent: <B>in</B>.
<BR>
Specified as: an integer variable <!-- MATH
 $-1\le root\le np-1$
 -->
<IMG
 WIDTH="140" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img75.png"
 ALT="$-1\le root\le np-1$">, default <IMG
 WIDTH="25" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="img76.png"
 ALT="$-1$">. 
</DD>
<DT><STRONG><B>On Return</B></STRONG></DT>
<DD>
</DD>
<DT><STRONG>glob_x</STRONG></DT>
<DD>The array where the local parts must be gathered.
<BR>
Scope: <B>global</B> 
<BR>
Type: <B>required</B>
<BR>
Intent: <B>out</B>.
<BR>
Specified as: a rank one or two array with the <code>ALLOCATABLE</code> attribute.
</DD>
<DT><STRONG>info</STRONG></DT>
<DD>Error code.
<BR>
Scope: <B>local</B> 
<BR>
Type: <B>required</B> 
<BR>
Intent: <B>out</B>.
<BR>
An integer value; 0 means no error has been detected. 
</DD>
</DL>

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