bstrap.tst2 = function(z, y, B, tst)
{
  n = length(z)
  m = length(y)
 
  x = c(z,y)
  bsamples = matrix(sample(x, size=(n+m)*B, replace=TRUE), nrow=B)
  tst.star = apply(bsamples, 1, function(x_) (tst(x_[1:n],x_[(n+1):(n+m)])) )
  
  return (tst.star)
}

tst.meandiff = function(z, y)
{
  mu.z = mean(z)
  mu.y = mean(y)

  return ( mu.z - mu.y )
}