<div class="gmail_quote">On Mon, Apr 23, 2012 at 21:20, Rajeev Thakur <span dir="ltr"><<a href="mailto:thakur@mcs.anl.gov">thakur@mcs.anl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div id=":2k9">One reason is that MPI_Accumulate allows only a restricted form of derived datatype, where all basic elements are of the same type. In MPI_Reduce you can pass any crazy datatype and you get to define the reduction operation for that.<br>
</div></blockquote><div><br></div><div>Is it somehow expensive to remember/determine that the datatype consists only of basic types, such that MPI_Reduce can process it in the same way that MPI_Accumulate does?</div></div>