Full_Name: Willa Chen Version: 2.7.2 OS: Window XP Submission from: (NULL) (128.122.182.70) The match function does not return value properly. See an example below. > a<-seq(0.6,1,by=0.01) > match(0.88,a) [1] 29 > match(0.89,a) [1] NA > match(0.90,a) [1] NA > match(0.91,a) [1] NA > match(0.92,a) [1] NA > match(0.93,a) [1] NA > match(0.94,a) [1] 35