[Rd] prod(numeric(0)) surprise

[Ben Bolker]

Duncan Murdoch wrote:
> On 1/8/2006 9:24 PM, Ben Bolker wrote:
> 
>>    It surprised me that prod(numeric(0)) is 1.
>> I guess if you say (operation(nothing) == identity
>> element) this makes sense, but ??
> 
> 
> What value were you expecting, or were you expecting an error?  I can't 
> think how any other value could be justified, and throwing an error 
> would make a lot of formulas more complicated.
> 
>>
> 
> 
> That's a fairly standard mathematical convention, which is presumably 
> why sum and prod work that way.
> 
> Duncan Murdoch

   OK.  I guess I was expecting NaN/NA (as opposed to an error),
but I take the "this makes everything else more complicated" point.
Should this be documented or is it just too obvious ... ?
(Funny -- I'm willing to take gamma(1)==1 without any argument
or suggestion that it should be documented ...)


   cheers
     Ben


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