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Implement Jackknife Using Parallel Computing

This example is from the jackknife function reference page, but runs in parallel.

Starting parpool using the 'local' profile ... connected to 2 workers.

mypool = 

  Pool with properties:

    AttachedFiles: {0x1 cell}
       NumWorkers: 2
      IdleTimeout: 30
          Cluster: [1x1 parallel.cluster.Local]
     RequestQueue: [1x1 parallel.RequestQueue]
      SpmdEnabled: 1
opts = statset('UseParallel',true);
sigma = 5;
y = normrnd(0,sigma,100,1);
m = jackknife(@var, y,1,'Options',opts);
n = length(y);
bias = -sigma^2 / n % known bias formula
jbias = (n - 1)*(mean(m)-var(y,1)) % jackknife bias estimate

bias =


jbias =


This simple example is not a good candidate for parallel computation:

% How long to compute in serial?
tic;m = jackknife(@var,y,1);toc
Elapsed time is 0.022771 seconds.

% How long to compute in parallel?
tic;m = jackknife(@var,y,1,'Options',opts);toc
Elapsed time is 0.299066 seconds.

jackknife does not use random numbers, so gives the same results every time, whether run in parallel or serial.