Re: [Haskell-cafe] practice problems?

Paul Johnson wrote:

"Brian Hulley" wrote:

...

What about a library for interval arithmetic [1]?

[Interval 5 5] / [Interval -1 1] = [FromNegInfinityTo -5, ToPosInfinityFrom 5]

Take a look at my Ranged Sets library at

http://sourceforge.net/projects/ranged-sets

Hi Paul - Thanks for the link to your lib (do you want to add a link from http://www.haskell.org/haskellwiki/Libraries_and_tools/Mathematics ?) I've only had time to have a brief look but it seems that RSet's could be used as interval arithmetic numbers with suitable instance decls for Num etc. My knowledge of interval arithmetic itself however is not sufficient to tell at this moment if the full generality of RSet's is actually needed ie perhaps it is enough to just say that division by a range containing zero should be undefined and perhaps there are no other ops which would cause more than one result range in which case it would be inefficient to use a more general representation than needed. Possibly there could be two different implementations of interval arithmetic - one allowing for multiple ranges and one that just treated division by an interval containing zero (and other problematic situations) to be undefined, so that the results of each op would be a single range when machine-level speed is needed and it is known in advance that division by zero etc will not happen in the specific problem domain. Anyway thanks for sharing your library with a nice BSD3 license! :-) Regards, Brian. -- Logic empowers us and Love gives us purpose. Yet still phantoms restless for eras long past, congealed in the present in unthought forms, strive mightily unseen to destroy us. http://www.metamilk.com