On Wed, 2010-01-13 at 20:31 -0500, Patrick Durusau wrote:
> Andreas,
>
> Andreas J. Guelzow wrote:
> > On Wed, 2010-01-13 at 17:29 -0500, wrote:
> >
> >> 2) What happens if the constraints are violated?
> >>
> >> Compare to RATE():
> >>
> >> If Nper is 0 or less than 0, the result is an error.
> >>
> >> Do we really mean to say that constraint violations are errors in some
> >> functions, but not in others?
> >>
> >
> > please see 5.2: "If a constraint is not met, the function/operator
> > should return an Error unless otherwise noted." This issue comes up
> > again and again. I guess that is the drawback of mentioning common
> > properties and behaviour only once!
> >
> >
There are surely lots of places in the description where we should have
constraints rather than talking about error returns.
> Made me curious about "error" and so:
>
> 5.4.5 Infix Operator "/" - "Dividing by zero returns an Error.
>
> Note that this operator is reported to have Constraints: *none*
This of course would be a perfect place for a constraint!
>
> 5.4.12 Infix Operator Reference Intersection ("!")
>
> > If for all intersections there are no cells in common and the result
> > list is empty, error #NULL! is returned.
This is really bad: We never define the #NULL! error (nor should we). In
fact the only error that we require is #NA!
> >
> 5.5.3 MINVERSE
>
> > If the matrix is not invertible, this function *should* return an
> > error value.
I am not quite sure whether we can/should formulate this as a
constraint.
> >
> That is just a sampling.
I didn;t say that we should never talk about errors, but failure to
satisfy a constraint should yield an error unless stated otherwise.
>
> Please assign the issue to me.
>
> I am less certain about the resolution, although obviously we need to be
> consistent, sometimes the difference in what is said may be meaningful.
>
> Suggest that we add an issue to JIRA to make a special effort to check
> the use of "error."
>
> Hope you are having a great evening!
And I hope you do too!
Andreas
--
Andreas J. Guelzow
Concordia University College of Alberta
