[clean-list] IEEE floating point and Clean

[M.Kesseler@aia.nl]

Siegfried Gonzi wrote:
>Therefore I thought it is enough in order to pleasure the IEEE rules
>when the computation does not break (especially the last few sentences;
>see above).

Well, I think the point that Kahan makes is as follows: in some cases the
IEEE rules yield valid results, but in some cases they don't. It all
depends on the computation. So, the IEEE rules (or Java) provide a false
sense of security.

>> This can be dangerous. Java provides no built-in way to check that
>> such a situation has occured. Clean does not either (as far as I know).
>
>Clean would behave the same as Java in this respect? And the paper could
>also be called?:
>
>"Why Clean's floating point hurts everyone everywhere"

Everyone everywhere? Perhaps (I almost said 'I hope so'... Oops). But:
- Kahan mentions a number of other Java-related problems too. I have not
  looked at these (yet).
- Does Clean make the same (portability) claims as Java does?
- How many other widely used languages have similar 'problems'?

>This is my motivation to figure this out whether it is true or not. And
>also to discuss whether Kahan is exaggeration the problem.

I don't think - although he's quite verbose - that he is exaggerating the
problem, but it IS questionable whether the problem affects you.
In the end, floating point calculations are hard, so one must be
careful in any programming language. But I do think that any
improvement in this area IS worthwhile considering.

regards,
Marco Kesseler

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