title: running multiple jobs in background at same time (parallel) in  r
body: <p>I want to run a program which need substantial time. I want to write a function that can run in parallel (I am graphical interface user in windows). The function divides the task into n sub-tasks and performs a final consensus task. I want to run n task at parallel( same time within same program window) and then combine the outputs. The following just an example:</p>
  
  <pre><code>ptm &lt;- proc.time()
  j1 &lt;- cov(mtcars[1:10,], use="complete.obs") # job 1
  j2 &lt;- cov(mtcars[11:20,], use="complete.obs") # job 2
  j3 &lt;- cov(mtcars[21:32,], use="complete.obs") # job 3
  proc.time() - ptm
  
  out &lt;- list (j1 = j1, j2 = j2, j3 = j3) 
  </code></pre>
  
  <p>I know in unix "&amp;" usually allows the jobs to run in background. Is there similar way in R </p>