Full_Name: Grégoire Talbot Version: 2.7.0 OS: windows 2000 Submission from: (NULL) (147.99.1.149) Try this : > a=seq(from=0.1,to=1,by=0.1) > a [1] 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Ok > a[1]==0.1 [1] TRUE Ok > a[3]==0.3 [1] FALSE !!! > a[3] [1] 0.3 !!! > a[3]=0.3 > a[3]==0.3 [1] TRUE ??????????????????????????