Message Passing Interface for parallel computing

The mpi package is a simplified wrapper to the OpenMPI C library designed to support algorithms for parallel computing.

This library allows a program to support parallel computations over the network. This is otherwise known as a single-program multiple-data (SPMD) architecture.

Requirements

• On ubuntu, you can install the OpenMPI library with:

sudo apt install libopenmpi-dev

• On Arch Linux, you can install the OpenMPI library with:

sudo pacman -S openmpi

• On macOS, you can install the OpenMPI library with:

brew install openmpi

• On Windows, you can install the OpenMPI library with:

choco install openmpi

• On FreeBSD, you can install the OpenMPI library with:

pkg install openmpi

Features

The mpi routines supported include:

• start() [deprecated]
• initialize()
• finalize()
• stop() [deprecated]
• world_rank() int
• world_size() int
• is_on() bool
• new_communicator(ranks []int) ?&Communicator

The methods for the Communicator support i32, u32, i64, u64, f32 and f64 data types. These allow exchange of arrays of data between processors or broadcast from the first processor (the root node with rank == 0).

A program must issue a send (on one rank) and matching receive on another rank or all ranks, depending on the nature of the method. Use barrier() to ensure all ranks are synchronized at that point.

Support is provided for Linux and the BSDs.

Once you have created a Communicator, you can use these methods, where the <type> is one of the above i32, u32, i64, u64, f32 or f64:

Method	Result
comm.rank()	Rank of the processor within the World or group
comm.size()	Size of the list of processors
comm.abort()	Abort the MPI program
comm.barrier()	Resynchronize all processors to this point
comm.send_i32( vals []i32, to_rank int)	Send an array to one rank
comm.recv_i32( vals []i32, from_rank int)	Receive array from one rank
comm.send_u32( ... )	As above for unsigned 32-bit integers
comm.send_i64( ... )	As above for signed 64-bit integers
comm.send_u64( ... )	As above for unsigned 64-bit integers
comm.send_f32( ... )	As above for 32-bit floats
comm.send_f64( ... )	As above for 64-bit floats
comm.send_one_<type>( val <type>, to_rank int)	Send one value to one rank
comm.recv_one_<type>( from_rank int) <type>	Returns one value from one rank
comm.bcast_from_root_<type>(vals []<type>)	Copy the values to all processors
comm.reduce_sum_<type>(mut dest []<type>, orig []<type>)	Sum orig array elements to dest on rank 0
comm.all_reduce_sum_<type>(mut dest []<type>, orig []<type>)	Sum orig array elements to dest on all ranks
comm.reduce_min_<type>(mut dest []<type>, orig []<type>)	Minimize orig array elements to dest on rank 0
comm.all_reduce_min_<type>(mut dest []<type>, orig []<type>)	Minimize orig array elements to dest on all ranks
comm.reduce_max_<type>(mut dest []<type>, orig []<type>)	Maximize orig array elements to dest on rank 0
comm.all_reduce_max_<type>(mut dest []<type>, orig []<type>)	Maximize orig array elements to dest on all ranks