require 'benchmark'
  include Benchmark          # we need the CAPTION and FORMAT constants

  n = 10000
  Benchmark.benchmark(CAPTION, 7, FORMAT, ">total:", ">avg:") do |x|
    tf = x.report("plain nc :")  { IO.popen("cdo -sinfov -timmean oceLong.nc   >/dev/null 2>&1").read }
    tt = x.report("plain nc4:")  { IO.popen("cdo -sinfov -timmean oceLong.nc4  >/dev/null 2>&1").read }
    tu = x.report("nc4   zip:")  { IO.popen("cdo -sinfov -timmean oceLong.nc4z >/dev/null 2>&1").read }
    [tf+tt+tu, (tf+tt+tu)/3]
  end