On 26/03/2010, at 12:38 PM, jim holtman wrote:
> WHen using '==' or '%in%' it is a equality test -- it has to equal zero. If
> you want a tolerance in the test, use 'all.equal'
>
> On Thu, Mar 25, 2010 at 5:29 PM, Dimitri Liakhovitski <ld7...@gmail.com>wrote:
>
>> Hello!
>>
>> I am wondering at what point does R consider a numeric value to be
>> equal to zero - for statements of the type x==0 and x %in% 0.
>>
>> Thank you very much!
There is still perhaps a question to be answered here. One can key in
a representation of a number, different from ``0'' and yet get a value
deemed to be 0 by the machine.
E.g. on my machine
> 1e-324 == 0
[1] TRUE
> 1e-323 == 0
[1] FALSE
The question of where the line is drawn is probably ill-posed or meaningless
or something like that. It's not clear to me what the issues are. Also the
answer, if there is a meaningful one, is likely to be machine dependent rather
than R dependent.
cheers,
Rolf Turner
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