At a minimum, the first statement needs "==".

Also, is.na() gives TRUE/FALSE.  While a logical comparison to NA gives NA
as a value.

Kevin



On Fri, May 3, 2013 at 10:24 AM, jpm miao <miaojpm@gmail.com> wrote:

> I have a program, when I write
>
> if(num!=NA)
>
> it yields an error message.
>
> However, if I write
>
> if(is.na(num)==FALSE)
>
> it works.
>
> Why doesn't the first statement work?
>
> Thanks,
>
> Miao
>
>         [[alternative HTML version deleted]]
>
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> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Kevin Wright

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