2001/10/15 Version 1.4: minimum and maximum points of
           histograms can now be specified.
2001/09/22 Version 1.3: incorporated weighted
           percentiles into function "pctile"; renamed
           functions "probn" and "npoint" to "probz" and
           "zpoint", respectively.
2001/09/15 Renamed functions "invprobchisq", "invprobf",
           "invprobn", and "invprobt" to "chisqpoint",
           "fpoint", "npoint", and "tpoint", resp.
2001/09/14 In version 1.2, the capabilites and syntax
           of functions "plotlinreg" and "plotlogreg"
           have been modified to allow processing of
           datasets that are partitioned.
