[Haskell-cafe] Interval Arithmetics

Mitar mmitar at gmail.com
Sun Aug 5 18:46:21 EDT 2007


First, disclaimer: everything I know about interval arithmetics comes
from this video:


I would like to know if there is any implementation of interval
arithmetics in Haskell? I would like to play a little with that. I
checked the web and the straightforward approach I found:


has from my point of view invalid implementation. For example, lower
bound in the sum should not be just calculated as the sum of lower
bounds of summands. It should return the greatest representable number
which is smaller or equal to the exact value of the sum. With just
boldly making a sum we ignore any errors we could introduce and this
is somehow against the idea of interval arithmetics.

And as it is said at the end of the talk, a system behind interval
arithmetics should do a lot of work to make those intervals as small
as possible while still correct and counting in all the errors we

I think a strict-typed and lazy language like Haskell would be a good
place to implement this. But I would like to know if this would be
possible to do from the language itself, without making changes to the
compiler and/or runtime itself? Because, for example, a good
implementation should reformulate equations at the runtime accordingly
to exact values it wants to compute them on.

Has it been done already?


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