[R] a < b < c is alway TRUE

[Philippe Grosjean]

>One of our students did something like:

>  x[a < b < c]

>instead of

>  x[a < b & b < c]


>But why is

>  3 < 2 < 1	# [1] TRUE ???


>Is there any reason?
>Or wouldn't it be better to get a warning / error?

>Uwe Ligges

The answer is simple: the first inequation 3 < 2 is solved, which gives
FALSE. Then the second inequation to be solved is: FALSE < 1. Since
as.numeric(FALSE) is 0, you have to solve 0 < 1, which is... TRUE. Hence,
this is not a bug, but an incorrect use of the R language.
Best regards,

Philippe Grosjean


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