mu.data = NULL
  print(xyplot(mopt~mirr,groups=mk,data=seriesdata,
          
               panel = panel.superpose,
               panel.groups = function(x, y, group.number, subscripts,..., lty, lwd) {
                 panel.xyplot(x, y,..., lty=lty, lwd=lwd)
 
                 mu.data = rbind(mu.data, data.frame(foo=bar))
                 print(mu.data)
     }
  )))
  dev.off()               
  
  print(mu.data)