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       MPI_Waitsome -  Waits for some given communications to complete


       #include <mpi.h>
       int MPI_Waitsome(int count, MPI_Request* reqs, int *ndone,
                       int *indices, MPI_Status *stats)


              - length of array_of_requests (integer)
       reqs   - array of requests (array of handles)


       ndone  - number of completed requests (integer)
              -  array  of  indices  of  operations  that  completed (array of
       stats  - array of status objects for operations that  completed  (array
              of Status), or the MPI constant MPI_STATUSES_IGNORE


       The  array  of  indicies are in the range 0 to incount - 1 for C and in
       the range 1 to incount for Fortran.

       Null requests are ignored; if all requests are null, then  the  routine
       returns with outcount set to MPI_UNDEFINED .


       For  send  operations, the only use of status is for MPI_Test_cancelled
       in the case that there is an error, in which case the  MPI_ERROR  field
       of status will be set.


       All  MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
       an additional argument ierr at the end of the argument list.   ierr  is
       an  integer and has the same meaning as the return value of the routine
       in C.  In Fortran, MPI routines are subroutines, and are  invoked  with
       the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in


       If an error occurs in an MPI function, the current MPI error handler is
       called  to  handle  it.   By default, this error handler aborts the MPI
       job.  The error handler may be changed with  MPI_Errhandler_set  ;  the
       predefined  error  handler MPI_ERRORS_RETURN may be used to cause error
       values to be returned (in C and Fortran; this  error  handler  is  less
       useful  in  with  the  C++  MPI bindings.  The predefined error handler
       MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the  error  value
       needs  to  be recovered).  Note that MPI does not guarantee that an MPI
       program can continue past an error.

       All MPI routines (except MPI_Wtime and  MPI_Wtick  )  return  an  error
       value;  C routines as the value of the function and Fortran routines in
       the last argument.  The C++  bindings  for  MPI  do  not  return  error
       values;  instead,  error values are communicated by throwing exceptions
       of type MPI::Exception (but  not  by  default).   Exceptions  are  only
       thrown if the error value is not MPI::SUCCESS .

       Note  that  if  the MPI::ERRORS_RETURN handler is set in C++, while MPI
       functions will return upon an error, there will be no  way  to  recover
       what the actual error value was.
              - No error; MPI routine completed successfully.
              -  Invalid  MPI_Request  ; either null or, MPI_REQUEST_NULL , in
              the case of a MPI_Start  or  MPI_Startall  ,  not  a  persistent
              - Invalid count argument.  Count arguments must be non-negative;
              a count of zero is often valid.
              - Invalid  argument.   Some  argument  is  invalid  and  is  not
              identified  by a specific error class.  This is typically a NULL
              pointer or other such error.

              - The actual error value is in the  MPI_Status  argument.   Note
              that   if   this   error   occurs   and   MPI_STATUS_IGNORE   or
              MPI_STATUSES_IGNORE was used as the status argument, the  actual
              error  will  be lost. This error class is returned only from the
              multiple-completion  routines  (  MPI_Testall  ,  MPI_Testany  ,
              MPI_Testsome  ,  MPI_Waitall , MPI_Waitany , and MPI_Waitsome ).
              The field MPI_ERROR in the status argument  contains  the  error
              value  or MPI_SUCCESS (no error and complete) or MPI_ERR_PENDING
              to indicate  that  the  request  has  not  completed.   The  MPI
              Standard  does  not  specify  what  the  result  of the multiple
              completion routines is when an error occurs.  For example, in an
              MPI_WAITALL  ,  does the routine wait for all requests to either
              fail or complete, or does it return immediately  (with  the  MPI
              definition of immediately, which means independent of actions of
              other MPI processes)?  LAM/MPI has chosen  to  make  the  return
              immediate  (alternately,  local  in  MPI  terms), and to use the
              error class MPI_ERR_PENDING (introduced in MPI 1.1) to  indicate
              which  requests  have  not  completed.   In most cases, only one
              request with an error will be detected in each call  to  an  MPI
              routine  that  tests  multiple requests.  The requests that have
              not been processed (because an  error  occured  in  one  of  the
              requests)   will   have   their   MPI_ERROR  field  marked  with
              MPI_ERR_PENDING .


       For more information, please see the official MPI Forum web site, which
       contains  the  text  of  both  the  MPI-1  and  MPI-2 standards.  These
       documents contain detailed information about each MPI function (most of
       which is not duplicated in these man pages).


       The  LAM Team would like the thank the MPICH Team for the handy program
       to       generate        man        pages        ("doctext"        from     ),    the    initial
       formatting, and some initial text for most of the MPI-1 man pages.