ECDF empirical cumulative function NaN's are considered Missing values and are ignored. [F,X] = ecdf(Y) calculates empirical cumulative distribution functions (i.e Kaplan-Meier estimate) ecdf(Y) ecdf(gca,Y) without output arguments plots the empirical cdf, in axis gca. Y input data must be a vector or matrix, in case Y is a matrix, the ecdf for every column is computed. see also: HISTO2, HISTO3, PERCENTILE, QUANTILE