Data with Missing Values
- nancumsum — This function returns
            the cumulative sum of the values of a matrix
- nand2mean — difference of the means of
            two independent samples
- nanmean — mean  (ignoring  Nan's)
- nanmeanf — mean (ignoring Nan's) with a given frequency.
- nanmedian — median of the  values of a numerical vector or matrix
- nanreglin — Linear regression
- nanstdev — standard deviation (ignoring the NANs).
- nansum — Sum of values ignoring NAN's
- thrownan — Eliminates nan values