<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html > <head><title>psb_sum — Global sum</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta name="generator" content="TeX4ht (http://www.tug.org/tex4ht/)"> <meta name="originator" content="TeX4ht (http://www.tug.org/tex4ht/)"> <!-- html,3 --> <meta name="src" content="userhtml.tex"> <link rel="stylesheet" type="text/css" href="userhtml.css"> </head><body > <!--l. 325--><div class="crosslinks"><p class="noindent">[<a href="userhtmlsu70.html" >next</a>] [<a href="userhtmlsu65.html" >prev</a>] [<a href="userhtmlsu65.html#tailuserhtmlsu65.html" >prev-tail</a>] [<a href="userhtmlsu63.html#tailuserhtmlsu66.html">tail</a>] [<a href="userhtmlsu59.html#userhtmlsu69.html" >up</a>] </p></div> <h4 class="subsectionHead"><span class="titlemark">7.10 </span> <a id="x78-1150007.10"></a>psb_sum — Global sum</h4> <div class="verbatim" id="verbatim-93"> call psb_sum(icontxt, dat, root) </div> <!--l. 329--><p class="nopar" > <!--l. 331--><p class="indent" > This subroutine implements a sum reduction operation based on the underlying communication library. <dl class="description"><dt class="description"> <span class="cmbx-10">Type:</span> </dt><dd class="description">Synchronous. </dd><dt class="description"> <span class="cmbx-10">On Entry</span> </dt><dd class="description"> </dd><dt class="description"> <span class="cmbx-10">icontxt</span> </dt><dd class="description">the communication context identifying the virtual parallel machine.<br class="newline" />Scope: <span class="cmbx-10">global</span>.<br class="newline" />Type: <span class="cmbx-10">required</span>.<br class="newline" />Intent: <span class="cmbx-10">in</span>.<br class="newline" />Specified as: an integer variable. </dd><dt class="description"> <span class="cmbx-10">dat</span> </dt><dd class="description">The local contribution to the global sum.<br class="newline" />Scope: <span class="cmbx-10">global</span>.<br class="newline" />Type: <span class="cmbx-10">required</span>.<br class="newline" />Intent: <span class="cmbx-10">inout</span>.<br class="newline" />Specified as: an integer, real or complex variable, which may be a scalar, or a rank 1 or 2 array.  Type, kind, rank and size must agree on all processes. </dd><dt class="description"> <span class="cmbx-10">root</span> </dt><dd class="description">Process to hold the final sum, or <span class="cmsy-10">-</span>1 to make it available on all processes.<br class="newline" />Scope: <span class="cmbx-10">global</span>.<br class="newline" />Type: <span class="cmbx-10">optional</span>.<br class="newline" />Intent: <span class="cmbx-10">in</span>.<br class="newline" />Specified as: an integer value <span class="cmsy-10">-</span>1 <span class="cmmi-10"><</span>= <span class="cmmi-10">root <</span>= <span class="cmmi-10">np </span><span class="cmsy-10">- </span>1, default -1.  </dd></dl> <!--l. 358--><p class="indent" > <dl class="description"><dt class="description"> <span class="cmbx-10">On Return</span> </dt><dd class="description"> </dd><dt class="description"> <span class="cmbx-10">dat</span> </dt><dd class="description">On destination process(es), the result of the sum operation.<br class="newline" />Scope: <span class="cmbx-10">global</span>.<br class="newline" />Type: <span class="cmbx-10">required</span>.<br class="newline" />Intent: <span class="cmbx-10">inout</span>.<br class="newline" />Specified as: an integer, real or complex variable, which may be a scalar, or a rank 1 or 2 array. <br class="newline" />Type, kind, rank and size must agree on all processes.</dd></dl> <!--l. 369--><p class="noindent" ><span class="cmbx-12">Notes</span> <ol class="enumerate1" > <li class="enumerate" id="x78-115002x1">The <span class="obeylines-h"><span class="verb"><span class="cmtt-10">dat</span></span></span> argument is both input and output, and its value may be changed even on processes different from the final result destination. </li> <li class="enumerate" id="x78-115004x2">The <span class="obeylines-h"><span class="verb"><span class="cmtt-10">dat</span></span></span> argument may also be a long integer scalar.</li></ol> <!--l. 379--><div class="crosslinks"><p class="noindent">[<a href="userhtmlsu70.html" >next</a>] [<a href="userhtmlsu65.html" >prev</a>] [<a href="userhtmlsu65.html#tailuserhtmlsu65.html" >prev-tail</a>] [<a href="userhtmlsu66.html" >front</a>] [<a href="userhtmlsu59.html#userhtmlsu69.html" >up</a>] </p></div> <!--l. 379--><p class="indent" > <a id="tailuserhtmlsu66.html"></a> </body></html>