title: R plot: Using italics and a variable in a title
body: <p>Using R 2.14.0 with windows 7, I want to include italics and a changing variable in my title using R plot().  Here's some code:</p>
  
  <pre><code>ps=c(1,2,3)
  
  layout(matrix(1:3,1,3))
  
  #this works but isn't what I want
  for(i in 1:3){
      plot(1,1,main=expression(paste(italic(p),'=5')))
  }
  #this doesn't work
  for(i in 1:3){
      plot(1,1,main=expression(paste(italic(p),'=',ps[i])))
  }
  #this doesn't work either
  for(i in 1:3){
      plot(1,1,main=paste(expression(paste(italic(p),'=')),ps[i]))
  }
  </code></pre>
  
  <p>What I want in the title is p[in italics]=the value of ps during that iteration.  For instance for the first iteration, "<em>p</em>=0.1"</p>
  
  <p>Any help would be appreciated.  Thanks.</p>