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Example
We'll put together things we've learned into an example program. This program uses collective operations to broadcast a value to all tasks and gather results from all tasks to task 0.
This example, flip.f90, available in $EXAMPLES/MPI_intro/flip, demonstrates these calls.
If we compile and run on the SP, we get
seaborg% mpxlf90 -o flip -qsuffix=f=f90 flip.f90 1501-510 Compilation successful for file flip.f90 seaborg% poe ./flip -procs 8 -nodes 1 subfilter: default repo mpccc will be charged Flipping coin 1000000 times on each task. Processor 1 got 499614 heads. Processor 0 got 499493 heads. Processor 3 got 500017 heads. Processor 2 got 500595 heads. Processor 5 got 499306 heads. Processor 4 got 499778 heads. Processor 6 got 500008 heads. Processor 7 got 500830 heads. Heads came up 49.99551392 percent of the time.
