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<head><title>psb_init &#8212; Initializes PSBLAS parallel environment</title> 
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   <h4 class="subsectionHead"><span class="titlemark">7.1   </span> <a 
 id="x69-1060007.1"></a>psb_init &#8212; Initializes PSBLAS parallel environment</h4>
                                                                  

                                                                  
   <div class="verbatim" id="verbatim-61">
call&#x00A0;psb_init(ctxt,&#x00A0;np,&#x00A0;basectxt,&#x00A0;ids)
</div>
<!--l. 11--><p class="nopar" >
<!--l. 13--><p class="indent" >   This subroutine initializes the PSBLAS parallel environment, defining a virtual
parallel machine.
     <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">np</span> </dt><dd 
class="description">Number of processes in the PSBLAS virtual parallel machine.<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. &#x00A0;Default: use all available processes.
     </dd><dt class="description">
<span 
class="cmbx-10">basectxt</span> </dt><dd 
class="description">the initial communication context. The new context will be defined
     from the processes participating in the initial one.<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. &#x00A0;Default: use MPI_COMM_WORLD.
     </dd><dt class="description">
<span 
class="cmbx-10">ids</span> </dt><dd 
class="description">Identities  of  the  processes  to  use  for  the  new  context;  the  argument  is
     ignored when <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">np</span></span></span> is not specified. This allows the processes in the new
     environment to be in an order different from the original one.<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. &#x00A0;Default: use the indices (0<span 
class="cmmi-10">&#x2026;</span><span 
class="cmmi-10">np </span><span 
class="cmsy-10">- </span>1).</dd></dl>
<!--l. 42--><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">ctxt</span> </dt><dd 
class="description">the communication context identifying the virtual parallel machine, type
     <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">psb_ctxt_type</span></span></span>.  Note  that  this  is  always  a  duplicate  of  <span class="obeylines-h"><span class="verb"><span 
class="cmtt-10">basectxt</span></span></span>,
     so  that  library  communications  are  completely  separated  from  other
     communication operations.<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">out</span>.<br 
class="newline" />Specified as: an integer variable.</dd></dl>
                                                                  

                                                                  
<!--l. 55--><p class="noindent" ><span 
class="cmbx-12">Notes</span>
     <ol  class="enumerate1" >
     <li 
  class="enumerate" id="x69-106002x1">A call to this routine must precede any other PSBLAS call.
     </li>
     <li 
  class="enumerate" id="x69-106004x2">It is an error to specify a value for <span 
class="cmmi-10">np </span>greater than the number of processes
     available in the underlying base parallel environment.</li></ol>
                                                                  

                                                                  
                                                                  

                                                                  
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