<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">The standard doesn’t specify this, though I recall us discussing this and IIRC agreeing that ndims equal to zero was well-defined and not an error. And there is nothing in the standard that suggests that it should be an error, just nothing that says it shouldn’t.<div><br></div><div>Bill</div><div><br><div>
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">William Gropp<br>Acting Director and Chief Scientist, NCSA</div><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Director, Parallel Computing Institute<br>Thomas M. Siebel Chair in Computer Science<br>University of Illinois Urbana-Champaign<br><br><br><br><br></div>
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<br><div><div>On Nov 8, 2016, at 11:40 PM, Gilles Gouaillardet <<a href="mailto:gilles@rist.or.jp">gilles@rist.or.jp</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Folks,<br><br><br>Does the standard specifiy the behavior of MPI_Dims_create() when the ndims argument is zero ?<br><br><br>the standard only says negative input values of dims[i] are erroneous, but does not say anything about ndims.<br><br>ndims is the number of Cartesian dimensions (integer), and though a negative number likely looks erroneous<br><br>to most of us, a zero value is incorrect from a mathematical point of view (and i wish i remembered that ...)<br><br><br>Could someone tell me how a zero value should be interpreted ?<br><br>(e.g. valid/invalid/up to the implementor ?)<br><br><br>FWIW, currently<br><br>in MPICH, this is a no-op.<br><br>In Open MPI, this is an error by default, but if parameter check is manually disabled, then this is a no-op too.<br><br><br>Cheers,<br><br><br>Gilles<br><br>_______________________________________________<br>mpi-comments mailing list<br><a href="mailto:mpi-comments@lists.mpi-forum.org">mpi-comments@lists.mpi-forum.org</a><br>https://lists.mpi-forum.org/mailman/listinfo/mpi-comments<br></blockquote></div><br></div></body></html>