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A few functions in the MPI interface return multiple values, even after
the error code is eliminated. This is dealt with in mpiJava
in various ways. Sometimes an MPI function initializes some
elements in an array and also returns a count of the number of elements
modified. In Java we typically return an array result, omitting the
count. The count can be obtained subsequently from the length
member of the array. Sometimes an MPI function initializes an object
conditionally and returns a separate flag to say if the operation
succeeded. In Java we typically return an object reference which is
null if the operation fails. Occasionally extra internal state
is added to an existing MPI class to hold extra results--for example
the Status class has extra state initialized by functions like
Waitany to hold the index value. Rarely none of these
methods work and we resort to defining auxilliary classes to hold
multiple results from a particular function.