(j3.2006) Interval arithmetic

[Robert Corbett]

Malcolm Cohen wrote:
> 
> Van Snyder wrote:
> 
>>As a consequence of my involvement with P1788, I have concluded that it
>>is impossible in general to provide reliable interval arithmetic with
>>other than an intrinsic type.
>>  
> 
> You might have concluded that, but that doesn't mean that it's true.  
> And you're conflating "intrinsic type" with "type the compiler knows 
> about".  A Fortran 2003 compiler of necessity knows about types other 
> than intrinsic type, viz C_PTR and C_FUNPTR.

Agreed.  However, I shall mention that I have had trouble convincing
even members of Sun's Fortran that anything defined in an intrinsic
module is fair game for special compiler knowledge.  I too use the
example of C_PTR and C_FUNPTR for that purpose.

> So you are saying that John Reid's IEEE modules are totally useless 
> because the compiler can just ignore what the user writes and spill 
> anywhere violating the IEEE standard? That's news to everyone who 
> implemented them.

I agree that the IEEE modules are useless, but for different reasons.
Given that members of the committee cannot agree which expressions are
affected by the IEEE modules and which are not, what good are they?

Bob Corbett