[R] Why can't R understand if(num!=NA)?

[David Winsemius]

> 
> On May 3, 2013, at 17:24 , jpm miao wrote:
> 
>> I have a program, when I write
>> 
>> if(num!=NA)
>> 
> snipped

On May 3, 2013, at 10:46 AM, peter dalgaard wrote:

> Because comparison with an unknown value yields an unknown result. 

Anything else would violate the Second Law of Thermodynamics. We cannot have comparisons reducing entropy, now can we? Uncertainty cannot run uphill.

-- 

David Winsemius
Alameda, CA, USA