<div>I have a question about MPI_GET_COUNT and MPI_GET_ELEMENTS. What do these functions exactly return?</div>
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<div>As I have read from the documentation (3.2.5) MPI_GET_COUNT returns the count of 'entries' of type 'datatype' received. According to me in example 4.12 (line 13) MPI_GET_COUNT should return 2 as we have sent two MPI_REAL types. The example however shows 1. Is this because as at when you send 2 types MPI transparently creates a new custom datatype (4.1.11) consisting of these two elements and thus the top-entry is 1?</div>
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<div>This, however should suggest that MPI_GET_COUNT always returns 1, or MPI_UNDEFINED on an error (eg unmached receive count or type). Is this correct?</div>
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<div>MPI_GET_ELEMENTS than receives what?</div>
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<div>How is the example (4.12) even working correctly when a custom datatype Type2 consists of two MPI_REALs and you want to receive two of those, eg 4 MPI_REALs?</div>
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<div>I am using the MPI 2.1 documentation (<a href="http://www.mpi-forum.org/docs/docs.html" target="_blank">http://www.mpi-forum.org/docs/docs.html</a> in hardcover)</div>
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<div>Regards, Thomas</div>