Transfer distributed array or gpuArray to local workspace
X = gather(A)
X = gather(C,lab)
X = gather(A) can operate inside an
pmode, or communicating job to gather together the elements of a codistributed
array, or outside an
spmd statement to gather the
elements of a distributed array. If you execute this inside an
pmode, or communicating job,
X is a replicated
array with all the elements of the array on every worker. If you execute
this outside an
an array in the local workspace, with the elements transferred from
the multiple workers.
X = gather(distributed(X)) or
= gather(codistributed(X)) returns the original array
X = gather(C,lab) converts a codistributed
C to a variant array
such that all of the elements are contained on worker
X is a 0-by-0 empty double on all other workers.
For a gpuArray input,
X = gather(A) transfers
the array elements from the GPU to the local workspace.
If the input argument to
gather is not a
distributed, a codistributed, or a gpuArray, the output is the same
as the input.
Distribute a magic square across your workers, then gather the
whole matrix onto every worker and then onto the client. This code
results in the equivalent of
M = magic(n) on all
workers and the client.
n = 10; spmd C = codistributed(magic(n)); M = gather(C) % Gather all elements to all workers end S = gather(C) % Gather elements to client
Gather all of the elements of
C onto worker
1, for operations that cannot be performed across distributed arrays.
n = 10; spmd C = codistributed(magic(n)); out = gather(C,1); if labindex == 1 % Characteristic sum for this magic square: characteristicSum = sum(1:n^2)/n; % Ensure that the diagonal sums are equal to the % characteristic sum: areDiagonalsEqual = isequal ... (trace(out),trace(flipud(out)),characteristicSum) end end
Lab 1: areDiagonalsEqual = 1
Gather all of the elements from a distributed array
n = 10; D = distributed(magic(n)); % Distribute array to workers M = gather(D) % Return array to client
Gather the results of a GPU operation to the MATLAB workspace.
G = gpuArray(rand(1024,1)); F = sqrt(G); % Input and output are both gpuArray W = gather(G); % Return array to workspace whos
Name Size Bytes Class F 1024x1 108 gpuArray G 1024x1 108 gpuArray W 1024x1 8192 double
gather assembles the codistributed
or distributed array in the workspaces of all the workers on which
it executes, or on the MATLAB® client, respectively, but not both.
If you are using
gather within an
spmd statement, the gathered array is
accessible on the client via its corresponding
see Access Worker Variables with Composites. If you are
gather in a communicating job, you can
return the gathered array to the client as an output argument from
gather function requires communication
between all the workers, you cannot gather data from all the workers
onto a single worker by placing the function inside a conditional
statement such as
if labindex == 1.