Creates a new communicator to which cartesian topology information is attached. dims is an array specifying the number of processes in each dimension. periods is an array of logical values specifying whether the grid is periodic or not in each dimension. reorder is a logical value indicating whether the processes may be reordered in the new topology.

C equivalent: MPI_Cart_create()

MPI::Comm#graph_create(index, edges, reorder)

Creates a new communicator to which graph topology information is attached. index is an array in which the i-th entry is the the total number of neighbors of the first i nodes. edges is a flattened array of the edge lists for nodes 0, 1, ...index.length reorder is a logical value indicating whether the processes may be reordered in the new topology.

C equivalent: MPI_Graph_create()

Attributes

MPI::Comm#attr_put(keyval, obj)

Sets the attribute associated with MPI::Keyval keyval and the receiver communicator to obj. Returns true.

C equivalent: MPI_Attr_put()

MPI::Comm#attr_get(keyval)

Returns the object attribute associated with MPI::Keyval keyval and the receiver communicator if one exists and nil otherwise.

C equivalent: MPI_Attr_get()

MPI::Comm#attr_delete(keyval)

Deletes the object attribute associated with MPI::Keyval keyval and the receiver communicator if one exists. Returns true.

C equivalent: MPI_Attr_delete()

Informational Methods

MPI::Comm#size()

Returns the size of the communicator.

C equivalent: MPI_Comm_size()

MPI::Comm#rank()

Returns the rank of the current process within the communicator.

C equivalent: MPI_Comm_rank()

MPI::Comm#group()

Returns a handle to the group of the receiver communicator.

C equivalent: MPI_Comm_group()

MPI::Comm#inter?()

Returns true if the receiver is an intercommunicator.

C equivalent: MPI_Comm_test_inter()

MPI::Comm#remote_size()

Returns the size of the remote communicator of the intercommunicator.

C equivalent: MPI_Comm_remote_size()

MPI::Comm#remote_group()

Returns the remote group communicator of the intercommunicator.

C equivalent: MPI_Comm_remote_group()

Topology Specific Information Methods

MPI::Comm#topo_test()

Returns MPI::Comm.GRAPH if the topology associated with the receiver communicator is a graph, MPI::Comm.CART if the topology is cartesian, and MPI::UNDEFINED if there is no associated topology.

C equivalent: MPI_Topo_test()

MPI::Comm#graphdims()

Returns an array of two elements: the first being an integer describing the number of nodes and the second being an integer describing the number of edges in the graph topology.

C equivalent: MPI_Graphdims_get()

MPI::Comm#graphdims_get()

An alias for MPI::Comm#graphdims().

C equivalent: MPI_Graphdims_get()

MPI::Comm#graph()

Returns an array of two elements containing the arrays index and edges as given to the MPI::Comm#graph_create() method, respectively.

C equivalent: MPI_Graph_get()

MPI::Comm#graph_get()

An alias for MPI::Comm#graph()

C equivalent: MPI_Graph_get()

MPI::Comm#cartdim()

Returns the number of dimensions in the cartesian topology attached to the receiver.

C equivalent: MPI_Cartdim_get()

MPI::Comm#cartdim_get()

An alias for MPI::Comm#cartdim().

C equivalent: MPI_Cartdim_get()

MPI::Comm#cart()

Returns an array of 3 elements containing a dims array, periods array, and coords array as given to cart_create().

C equivalent: MPI_Cart_get()

MPI::Comm#cart_get()

An alias for MPI::Comm#cart()

C equivalent: MPI_Cart_get()

MPI::Comm#cart_rank(coords)

Returns the rank of the process at the coordinates given in the array coords.

C equivalent: MPI_Cart_rank()

MPI::Comm#cart_coords(rank)

Returns an array of the coordinates of the process specified by rank.

C equivalent: MPI_Cart_coords()

MPI::Comm#graph_neigbhors_count(rank)

Returns an integer specifying the number of neighbors of the process specified by rank.

C equivalent: MPI_Graph_neighbors_count()

MPI::Comm#graph_neigbhors(rank)

Returns an array of the ranks of the neighbors of the process specified by rank.

C equivalent: MPI_Graph_neighbors()

MPI::Comm#cart_shift(dir, disp)

Returns an array of two elements containing the rank of the source process and the rank of the destination process, respectively, as might be used in MPI::Comm#sendrecv(). dir indicates the direction of the shift and disp indicates the displacement.

C equivalent: MPI_Cart_shift()

MPI::Comm#cart_map(dims, periods)

Returns an integer specifying the optimal placement for the calling process on the physical machine. dims and periods are as for MPI::Comm#cart_create().

C equivalent: MPI_Cart_map()

MPI::Comm#graph_map(index, edges)

Returns an integer specifying the optimal placement for the calling process on the physical machine. index and edges are as for MPI::Comm#graph_create()

C equivalent: MPI_Graph_map()

Point-to-Point Communications

MPI::Comm#send(obj, dest, tag)

Sends object obj to process dest within the communicator with tag tag. Returns true on success.

C equivalent: MPI_Send()

MPI::Comm#recv(src, tag)

Receives an object from process src within the communicator with tag tag. Returns an array of two elements containing the object received and an MPI::Status object, respectively.

C equivalent: MPI_Recv()

MPI::Comm#bsend(obj, dest, tag)

Sends object obj to process dest within the communicator with tag tag. Buffering is used (see MPI::Comm#buffer_for()). Returns true on success.

C equivalent: MPI_Bsend()

MPI::Comm#ssend(obj, dest, tag)

Sends object obj to process dest within the communicator with tag tag synchronously. Returns true on success.

C equivalent: MPI_Ssend()

MPI::Comm#rsend(obj, dest, tag)

Sends object obj to process dest within the communicator with tag tag with the assumption that the receiver has already begun a receiving call. Returns true on success.

C equivalent: MPI_Rsend()

MPI::Comm#sendrecv(obj, dest, dtag, src, stag)

Sends object obj to process dest within the communicator with tag dtag and simultaneously starts a receive from process src with tag stag. Returns an array of two elements containing the object received and an MPI::Status object, respectively.

C equivalent: MPI_Sendrecv()

Non-blocking Point-to-Point Communications

MPI::Comm#isend(obj, dest, tag)

Performs a non-blocking send of object obj to process dest within the communicator with tag tag. Returns a new MPI::Request object.

C equivalent: MPI_Isend()

MPI::Comm#irecv(src, tag)

Performs a non-blocking receive of an object from process src within the communicator with tag tag. Returns a new MPI::Request object.

C equivalent: MPI_Irecv()

MPI::Comm#ibsend(obj, dest, tag)

Performs a non-blocking send of object obj to process dest within the communicator with tag tag. Buffering is used (see MPI::Comm#buffer_for()). Returns a new MPI::Request object.

C equivalent: MPI_Ibsend()

MPI::Comm#issend(obj, dest, tag)

Performs a non-blocking, synchronous send of object obj to process dest within the communicator with tag tag tag tag syncronously. Returns a new MPI::Request object.

C equivalent: MPI_Issend()

MPI::Comm#irsend(obj, dest, tag)

Performs a non-blocking send of object obj to process dest within the communicator with tag tag with the assumption that the receiver has already begun a receiving call. Returns a new MPI::Request object.

C equivalent: MPI_Irsend()

Persistent Communications

MPI::Comm#send_init(obj, dest, tag)

Sets up a persistent send of object obj to process dest within the communicator with tag tag. Returns a new MPI::Request object.

C equivalent: MPI_Send_init()

MPI::Comm#recv_init(src, tag)

Sets up a persistent receive of an object from process src within the communicator with tag tag. Returns a new MPI::Request object.

C equivalent: MPI_Recv_init()

MPI::Comm#bsend_init(obj, dest, tag)

Sets up a persistent send of object obj to process dest within the communicator with tag tag. Buffering is used (see MPI::Comm#buffer_for()). Returns a new MPI::Request object.

C equivalent: MPI_Bsend_init()

MPI::Comm#ssend_init(obj, dest, tag)

Sets up a persistent, synchronous send of object obj to process dest within the communicator with tag tag tag tag syncronously. Returns a new MPI::Request object.

C equivalent: MPI_Ssend_init()

MPI::Comm#rsend_init(obj, dest, tag)

Sets up a persistent send of object obj to process dest within the communicator with tag tag with the assumption that the receiver has already begun a receiving call. Returns a new MPI::Request object.

C equivalent: MPI_Rsend_init()

Buffering Methods

MPI::Comm#buffer_for(ary)

Sets up buffering on the receiver communicator to account for the objects in the array ary. Returns true.

C equivalent: MPI_Buffer_attach()

MPI::Comm#unbuffer()

Removes the buffer associated with the receiver communicator. Returns true.

C equivalent: MPI_Buffer_detach()

Collective Operations

MPI::Comm#barrier()

Performs a barrier operation on the communicator.

C equivalent: MPI_Barrier()

MPI::Comm#bcast(obj, root)

Broadcasts obj from process root to all other processes. The value of obj is irrelevant for all processes other than root. Returns a copy of obj all processes other than root and obj itself on process root.

C equivalent: MPI_Bcast

MPI::Comm#gather(obj, root)

Gathers obj from all processes in the communicator into an array and returns this array at process root. Given a rank r, the r-th element of the array is a copy of obj on process r. Returns true on all processes other than root.

C equivalent: MPI_Gather(), MPI_Gatherv()

MPI::Comm#allgather(obj)

Gathers obj from all processes in the communicator into an array and returns this array at all processes. Given a rank r, the r-th element of the array is a copy of obj on process r.

C equivalent: MPI_Allgather(), MPI_Allgatherv()

MPI::Comm#scatter(ary, root)

Scatters the contents of the array ary on the process with rank root to all processes in the communicator. The array must have length equal to the number of processes in the communicator. Returns the i-th object in ary at the i-th process.

C equivalent: MPI_Scatter()

MPI::Comm#alltoall(ary)

Scatters the contents of the array ary on every process to all processes in the communicator. The array must have length equal to the number of processes in the communicator. Returns an array on each process where the i-th object in the array on the j-th process is j-th object in ary at the i-th process.

C equivalent: MPI_Alltoall()

MPI::Comm#reduce(obj, op, root)

Reduces the object obj given using the MPI::Op op and returns the result of the reduction on the process with rank root. On all other processes, the method returns true. If obj is an array, it must have the same length on all processes and the operation is applied to each object in the array. To perform an operation on an array, pass an array of the array to which the operation will be applied.

C equivalent: MPI_Reduce()

MPI::Comm#allreduce(obj, op)

Reduces the object obj given using the MPI::Op op and returns the result of the reduction to all processes. If obj is an array, it must have the same length on all processes and the operation is applied to each object in the array. To perform an operation on an array, pass an array of the array to which the operation will be applied.

C equivalent: MPI_Allreduce()

MPI::Comm#scan(obj, op)

At each process i, returns the value of a reduction on processes 0...i, inclusively. If obj is an array, it must have the same length on all processes and the operation is applied to each object in the array. To perform an operation on an array, pass an array of the array to which the operation will be applied.

C equivalent: MPI_Scan()

MPI::Comm#reduce_scatter(ary, counts, op)

Performs an element-wise reduction on ary with MPI::Op op and scatters the result according to the array counts. Process 0 receives an array of the first counts[0] elements of the result of the reduction, process 1 receives an array of the next counts[1] elements of the result of the reduction, and so on. ary must have the same length on all processes and this length must equal the sum of the values in counts.

C equivalent: MPI_Reduce_scatter()

Probing

MPI::Comm#probe(src, tag)

Blocks until a message is available from process src with tag tag. Returns a new MPI::Status object.

C equivalent: MPI_Probe()

MPI::Comm#iprobe(src, tag)

Returns an array of two elements. The first element is a flag which is true if there is a message from the given source src with the given tag. If the flag is true, then the second element of the return array is a new MPI::Status object. If the flag is false, the second element of the return array is to be ignored.

C equivalent: MPI_Iprobe()

Comparison

MPI::Comm#==(comm)

Returns true if the receiver and the given communicator comm are the same communicator. Returns false otherwise.

C equivalent: MPI_Comm_compare()

MPI::Comm#congruent?(comm)

Returns true if the receiver and the given communicator comm are precisely congruent. Returns false otherwise.

C equivalent: MPI_Comm_compare()

MPI::Comm#similar?(comm)

Returns true if the receiver and the given communicator comm are precisely similar. Returns false otherwise.

C equivalent: MPI_Comm_compare()

Abortive Methods

MPI::Comm#abort(errorcode)

Aborts the MPI program with the given error code.

C equivalent: MPI_Abort()

Constants

MPI::Comm.ANY_TAG

A value which may be passed to any method expecting a tag.  It specifies
that any tag will match in that call.

MPI::Comm.ANY_SOURCE

A value which may be passed to any method expecting a source rank.  It 
specifies that any source rank will match in that call.

Notes

The MPI binding to Ruby is intended solely for Single Program, Multiple Data (SPMD) parallel computations. Thus, none of these communication methods can be intermixed with MPI programs written in other languages.

Because of the Multiple Data aspect, sending objects should be viewed as creating a copy of the original object on the recipient process. There are no remote method invocation concepts explicitly supported in this binding.

Contact Emil Ong about issues concerning this page.