<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html > <head><title>psb_cdall — Allocates a communication descriptor</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. 8--><div class="crosslinks"><p class="noindent">[<a href="userhtmlsu34.html" >next</a>] [<a href="userhtmlsu28.html#tailuserhtmlsu30.html">tail</a>] [<a href="userhtmlsu32.html#userhtmlsu33.html" >up</a>] </p></div> <h4 class="subsectionHead"><span class="titlemark">6.1 </span> <a id="x41-780006.1"></a>psb_cdall — Allocates a communication descriptor</h4> <div class="verbatim" id="verbatim-56"> call psb_cdall(icontxt, desc_a, info,mg=mg,parts=parts)  <br />call psb_cdall(icontxt, desc_a, info,vg=vg,[mg=mg,flag=flag])  <br />call psb_cdall(icontxt, desc_a, info,vl=vl,[nl=nl,globalcheck=.false.,lidx=lidx])  <br />call psb_cdall(icontxt, desc_a, info,nl=nl)  <br />call psb_cdall(icontxt, desc_a, info,mg=mg,repl=.true.) </div> <!--l. 16--><p class="nopar" > <!--l. 18--><p class="indent" > This subroutine initializes the communication descriptor associated with an index space. One of the optional arguments <span class="obeylines-h"><span class="verb"><span class="cmtt-10">parts</span></span></span>, <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vg</span></span></span>, <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span>, <span class="obeylines-h"><span class="verb"><span class="cmtt-10">nl</span></span></span> or <span class="obeylines-h"><span class="verb"><span class="cmtt-10">repl</span></span></span> must be specified, thereby choosing the specific initialization strategy. <dl class="description"><dt class="description"> <span class="cmbx-10">On Entry</span> </dt><dd class="description"> </dd><dt class="description"> <span class="cmbx-10">Type:</span> </dt><dd class="description">Synchronous. </dd><dt class="description"> <span class="cmbx-10">icontxt</span> </dt><dd class="description">the communication context.<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 value. </dd><dt class="description"> <span class="cmbx-10">vg</span> </dt><dd class="description">Data allocation: each index <span class="cmmi-10">i </span><span class="cmsy-10">∈{</span>1<span class="cmmi-10">…</span><span class="cmmi-10">mg</span><span class="cmsy-10">} </span>is allocated to process <span class="cmmi-10">vg</span>(<span class="cmmi-10">i</span>).<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 array. </dd><dt class="description"> <span class="cmbx-10">flag</span> </dt><dd class="description">Specifies whether entries in <span class="cmmi-10">vg </span>are zero- or one-based.<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 0<span class="cmmi-10">,</span>1, default 0. </dd><dt class="description"> <span class="cmbx-10">mg</span> </dt><dd class="description">the (global) number of rows of the problem.<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. It is required if <span class="obeylines-h"><span class="verb"><span class="cmtt-10">parts</span></span></span> or <span class="obeylines-h"><span class="verb"><span class="cmtt-10">repl</span></span></span> is specified, it is optional if <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vg</span></span></span> is specified. </dd><dt class="description"> <span class="cmbx-10">parts</span> </dt><dd class="description">the subroutine that defines the partitioning scheme.<br class="newline" />Scope:<span class="cmbx-10">global</span>.<br class="newline" />Type:<span class="cmbx-10">required</span>.<br class="newline" />Specified as: a subroutine. </dd><dt class="description"> <span class="cmbx-10">vl</span> </dt><dd class="description">Data allocation: the set of global indices <span class="cmmi-10">vl</span>(1 : <span class="cmmi-10">nl</span>) belonging to the calling process. <br class="newline" />Scope:<span class="cmbx-10">local</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 array. </dd><dt class="description"> <span class="cmbx-10">nl</span> </dt><dd class="description">Data allocation: in a generalized block-row distribution the number of indices belonging to the current process. <br class="newline" />Scope:<span class="cmbx-10">local</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. May be specified together with <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span>. </dd><dt class="description"> <span class="cmbx-10">repl</span> </dt><dd class="description">Data allocation: build a replicated index space (i.e. all processes own all indices).<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: the logical value <span class="obeylines-h"><span class="verb"><span class="cmtt-10">.true.</span></span></span> </dd><dt class="description"> <span class="cmbx-10">globalcheck</span> </dt><dd class="description">Data allocation: do global checks on the local index lists <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span><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: a logical value, default: <span class="obeylines-h"><span class="verb"><span class="cmtt-10">.false.</span></span></span> </dd><dt class="description"> <span class="cmbx-10">lidx</span> </dt><dd class="description">Data allocation: the set of local indices <span class="cmmi-10">lidx</span>(1 : <span class="cmmi-10">nl</span>) to be assigned to the global indices <span class="cmmi-10">vl</span>. <br class="newline" />Scope:<span class="cmbx-10">local</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 array.</dd></dl> <!--l. 86--><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">desc</span><span class="cmbx-10">_a</span> </dt><dd class="description">the communication descriptor.<br class="newline" />Scope:<span class="cmbx-10">local</span>.<br class="newline" />Type:<span class="cmbx-10">required</span>.<br class="newline" />Intent: <span class="cmbx-10">out</span>.<br class="newline" />Specified as: a structured data of type <a href="userhtmlsu5.html#descdata"><span class="cmtt-10">psb</span><span class="cmtt-10">_desc</span><span class="cmtt-10">_type</span></a>. </dd><dt class="description"> <span class="cmbx-10">info</span> </dt><dd class="description">Error code.<br class="newline" />Scope: <span class="cmbx-10">local </span><br class="newline" />Type: <span class="cmbx-10">required </span><br class="newline" />Intent: <span class="cmbx-10">out</span>.<br class="newline" />An integer value; 0 means no error has been detected.</dd></dl> <!--l. 100--><p class="noindent" ><span class="cmbx-12">Notes</span> <ol class="enumerate1" > <li class="enumerate" id="x41-78002x1">One of the optional arguments <span class="obeylines-h"><span class="verb"><span class="cmtt-10">parts</span></span></span>, <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vg</span></span></span>, <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span>, <span class="obeylines-h"><span class="verb"><span class="cmtt-10">nl</span></span></span> or <span class="obeylines-h"><span class="verb"><span class="cmtt-10">repl</span></span></span> must be specified, thereby choosing the initialization strategy as follows: <dl class="description"><dt class="description"> <span class="cmbx-10">parts</span> </dt><dd class="description">In this case we have a subroutine specifying the mapping between global indices and process/local index pairs. If this optional argument is specified, then it is mandatory to specify the argument <span class="obeylines-h"><span class="verb"><span class="cmtt-10">mg</span></span></span> as well. The subroutine must conform to the following interface: <div class="verbatim" id="verbatim-57">   interface  <br />     subroutine psb_parts(glob_index,mg,np,pv,nv)  <br />       integer, intent (in)  :: glob_index,np,mg  <br />       integer, intent (out) :: nv, pv(*)  <br />     end subroutine psb_parts  <br />  end interface </div> <!--l. 118--><p class="nopar" > The input arguments are: <dl class="description"><dt class="description"> <span class="cmbx-10">glob</span><span class="cmbx-10">_index</span> </dt><dd class="description">The global index to be mapped; </dd><dt class="description"> <span class="cmbx-10">np</span> </dt><dd class="description">The number of processes in the mapping; </dd><dt class="description"> <span class="cmbx-10">mg</span> </dt><dd class="description">The total number of global rows in the mapping;</dd></dl> <!--l. 125--><p class="noindent" >The output arguments are: <dl class="description"><dt class="description"> <span class="cmbx-10">nv</span> </dt><dd class="description">The number of entries in <span class="obeylines-h"><span class="verb"><span class="cmtt-10">pv</span></span></span>; </dd><dt class="description"> <span class="cmbx-10">pv</span> </dt><dd class="description">A vector containing the indices of the processes to which the global index should be assigend; each entry must satisfy 0 <span class="cmsy-10">≤</span> <span class="cmmi-10">pv</span>(<span class="cmmi-10">i</span>) <span class="cmmi-10">< np</span>; if <span class="cmmi-10">nv > </span>1 we have an index assigned to multiple processes, i.e. we have an overlap among the subdomains.</dd></dl> </dd><dt class="description"> <span class="cmbx-10">vg</span> </dt><dd class="description">In this case the association between an index and a process is specified via an integer vector <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vg(1:mg)</span></span></span>; each index <span class="cmmi-10">i </span><span class="cmsy-10">∈{</span>1<span class="cmmi-10">…</span><span class="cmmi-10">mg</span><span class="cmsy-10">} </span>is assigned to process <span class="cmmi-10">vg</span>(<span class="cmmi-10">i</span>). The vector <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vg</span></span></span> must be identical on all calling processes; its entries may have the ranges (0<span class="cmmi-10">…</span><span class="cmmi-10">np </span><span class="cmsy-10">- </span>1) or (1<span class="cmmi-10">…</span><span class="cmmi-10">np</span>) according to the value of <span class="obeylines-h"><span class="verb"><span class="cmtt-10">flag</span></span></span>. The size <span class="cmmi-10">mg </span>may be specified via the optional argument <span class="obeylines-h"><span class="verb"><span class="cmtt-10">mg</span></span></span>; the default is to use the entire vector <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vg</span></span></span>, thus having <span class="obeylines-h"><span class="verb"><span class="cmtt-10">mg=size(vg)</span></span></span>. </dd><dt class="description"> <span class="cmbx-10">vl</span> </dt><dd class="description">In this case we are specifying the list of indices <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl(1:nl)</span></span></span> assigned to the current process; thus, the global problem size <span class="cmmi-10">mg </span>is given by the range of the aggregate of the individual vectors <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span> specified in the calling processes. The size may be specified via the optional argument <span class="obeylines-h"><span class="verb"><span class="cmtt-10">nl</span></span></span>; the default is to use the entire vector <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span>, thus having <span class="obeylines-h"><span class="verb"><span class="cmtt-10">nl=size(vl)</span></span></span>. If <span class="obeylines-h"><span class="verb"><span class="cmtt-10">globalcheck=.true.</span></span></span> the subroutine will check how many times each entry in the global index space (1<span class="cmmi-10">…</span><span class="cmmi-10">mg</span>) is specified in the input lists <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span>, thus allowing for the presence of overlap in the input, and checking for “orphan” indices. If <span class="obeylines-h"><span class="verb"><span class="cmtt-10">globalcheck=.false.</span></span></span>, the subroutine will not check for overlap, and may be significantly faster, but the user is implicitly guaranteeing that there are neither orphan nor overlap indices. </dd><dt class="description"> <span class="cmbx-10">lidx</span> </dt><dd class="description">The optional argument <span class="obeylines-h"><span class="verb"><span class="cmtt-10">lidx</span></span></span> is available for those cases in which the user has already established a global-to-local mapping; if it is specified, each index in <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl(i)</span></span></span> will be mapped to the corresponding local index <span class="obeylines-h"><span class="verb"><span class="cmtt-10">lidx(i)</span></span></span>. When specifying the argument <span class="obeylines-h"><span class="verb"><span class="cmtt-10">lidx</span></span></span> the user would also likely employ <span class="obeylines-h"><span class="verb"><span class="cmtt-10">lidx</span></span></span> in calls to <span class="obeylines-h"><span class="verb"><span class="cmtt-10">psb_cdins</span></span></span> and <span class="obeylines-h"><span class="verb"><span class="cmtt-10">local</span></span></span> in calls to <span class="obeylines-h"><span class="verb"><span class="cmtt-10">psb_spins</span></span></span> and <span class="obeylines-h"><span class="verb"><span class="cmtt-10">psb_geins</span></span></span>; see also sec. <a href="userhtmlsu3.html#x9-70002.3.1">2.3.1<!--tex4ht:ref: sec:usermaps --></a>. </dd><dt class="description"> <span class="cmbx-10">nl</span> </dt><dd class="description">If this argument is specified alone (i.e. without <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span>) the result is a generalized row-block distribution in which each process <span class="cmmi-10">I </span>gets assigned a consecutive chunk of <span class="cmmi-10">N</span><sub><span class="cmmi-7">I</span></sub> = <span class="cmmi-10">nl </span>global indices. </dd><dt class="description"> <span class="cmbx-10">repl</span> </dt><dd class="description">This arguments specifies to replicate all indices on all processes. This is a special purpose data allocation that is useful in the construction of some multilevel preconditioners.</dd></dl> </li> <li class="enumerate" id="x41-78004x2">On exit from this routine the descriptor is in the build state. </li> <li class="enumerate" id="x41-78006x3">Calling the routine with <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vg</span></span></span> or <span class="obeylines-h"><span class="verb"><span class="cmtt-10">parts</span></span></span> implies that every process will scan the entire index space to figure out the local indices. </li> <li class="enumerate" id="x41-78008x4">Overlapped indices are possible with both <span class="obeylines-h"><span class="verb"><span class="cmtt-10">parts</span></span></span> and <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span> invocations. </li> <li class="enumerate" id="x41-78010x5">When the subroutine is invoked with <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span> in conjunction with <span class="obeylines-h"><span class="verb"><span class="cmtt-10">globalcheck=.true.</span></span></span>, it will perform a scan of the index space to search for overlap or orphan indices. </li> <li class="enumerate" id="x41-78012x6">When the subroutine is invoked with <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span> in conjunction with <span class="obeylines-h"><span class="verb"><span class="cmtt-10">globalcheck=.false.</span></span></span>, no index space scan will take place. Thus it is the responsibility of the user to make sure that the indices specified in <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vl</span></span></span> have neither orphans nor overlaps; if this assumption fails, results will be unpredictable. </li> <li class="enumerate" id="x41-78014x7">Orphan and overlap indices are impossible by construction when the subroutine is invoked with <span class="obeylines-h"><span class="verb"><span class="cmtt-10">nl</span></span></span> (alone), or <span class="obeylines-h"><span class="verb"><span class="cmtt-10">vg</span></span></span>.</li></ol> <!--l. 198--><div class="crosslinks"><p class="noindent">[<a href="userhtmlsu34.html" >next</a>] [<a href="userhtmlsu30.html" >front</a>] [<a href="userhtmlsu32.html#userhtmlsu33.html" >up</a>] </p></div> <!--l. 198--><p class="indent" > <a id="tailuserhtmlsu30.html"></a> </body></html>