exportPattern("^[[:alpha:]]+")
importFrom("grDevices", "dev.new", "xy.coords")
importFrom("graphics", "abline", "arrows", "barplot", "legend", "plot", 
           "points", "segments", "symbols", "text", "par", "rect", 
           "strheight", "strwidth", "axis", "box")
importFrom("stats", "cor", "cov", "qchisq", "sd", "runif")
importFrom("grDevices", "dev.off", "png")
