[R] accuracy of test cases

[Robin Hankin]

On Apr 29, 2005, at 11:51 am, Uwe Ligges wrote:

> Robin Hankin wrote:

[snip]
>> The tolerance should be as small as possible, but If I make it too 
>> small, the test may fail
>> when executed on a machine with different architecture from mine.
>> How do I deal with this?
>
> See ?all.equal
>
> Uwe Ligges
>

Hi Uwe

Thanks for this.  But sometimes my tests fail (right at the edge of a 
very wibbly wobbly
function's domain, for example) even with all.equal()'s default 
tolerance.

Maybe I should only include  tests where all.equal() passes 
"comfortably" on my
machine, and have done with it.  Yes,  this is the way to think about 
it: I
  was carrying out tests where one might
expect them to fail (entrapment?).  My mistake was to focus on the 
magnitude of
"tol" and to blithely include tests  where all.equal() failed, or came 
close to failing.

Unfortunately, all the interesting stuff happens at the boundary.

I guess (thinking about it again) that in such circumstances, there is 
no generic answer.


best wishes

rksh





--
Robin Hankin
Uncertainty Analyst
Southampton Oceanography Centre
European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743