Thanks, I know.
On Apr 26, 2010, at 10:28 PM, Pete Manolios wrote: > Exact rational arithmetic is clean and convenient to reason about > (that's what ACL2 uses), but a major problem is that one often really > wants the reals. For example, are you sure you won't need operations > such as square root? pi? e? log? sin? ... > > Another problem is that if a lot of computation is involved, then > exact rational arithmetic can easily get really slow. > > If you decide you want the reals, chances are you'll decide to give up > on exactness. One option to consider then, is to explicitly specify > the error bounds you are willing to tolerate. Then you can use > techniques such as interval arithmetic. > > Pete > > On Mon, Apr 26, 2010 at 9:02 PM, Matthias Felleisen > <matth...@ccs.neu.edu> wrote: >> >> I thought it was obvious that I had an exact rational arithmetic in mind, >> with ways to translate them into printable amounts. Furthermore, in case >> you're wondering, I would also specify the FFI to force the foreign language >> to use the same operations as the DSL and to not provide any conversions to >> and from this data type to a 'foreign' datatype. -- Matthias >> >> >> >> On Apr 26, 2010, at 7:36 PM, Pete Manolios wrote: >> >>> Following the IEEE 754 floating-point spec is not easy. For example, >>> see "The pitfalls of verifying floating-point computations" by David >>> Monniaux. Even if floating point is handled in a reasonable way, it is >>> still floating point, so many "obvious" properties, like associativity >>> of addition, do not hold. That is, there is no way to satisfy >>> Matthias' criterion number 2 if we use floating point (unless >>> "intended mathematical meaning" below means IEEE floating point). >>> >>> 2 Programs should have the intended mathematical meaning. >>> >>> >>> >>> On Mon, Apr 26, 2010 at 6:19 PM, Paul Steckler <st...@stecksoft.com> wrote: >>>> R6RS suggests, but doesn't require, that Scheme implementations follow >>>> the IEEE 754 floating-point spec. >>>> So you don't get behavior guarantees simply by choosing "Scheme" as >>>> your language. >>>> >>>> Years ago, Turbo Pascal had a binary-coded decimal (BCD) type that was >>>> especially suited for doing >>>> financial calculations, avoiding some of the representational problems >>>> of IEEE 754. Something like >>>> that might figure in a DSL for the feds. >>>> >>>> -- Paul >>>> >>>> On Tue, Apr 27, 2010 at 12:31 AM, Matthias Felleisen >>>> <matth...@ccs.neu.edu> wrote: >>>>> >>>>> Following Jay's and Jordan's example I have submitted my own response. A >>>>> scribbled version is available at: >>>>> >>>>> >>>>> http://www.ccs.neu.edu/home/matthias/Thoughts/Python_for_Asset-Backed_Securities.html >>>>> >>>>> Thanks for all the feedback -- Matthias >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> PRL mailing list >>>> p...@lists.ccs.neu.edu >>>> https://lists.ccs.neu.edu/bin/listinfo/prl >>>> >>> >>> >>> >>> -- >>> Pete Manolios >>> Northeastern University >>> http://www.ccs.neu.edu/home/pete >> >> > > > > -- > Pete Manolios > Northeastern University > http://www.ccs.neu.edu/home/pete _________________________________________________ For list-related administrative tasks: http://list.cs.brown.edu/mailman/listinfo/plt-dev
