On Fri, Aug 22, 2008 at 5:06 PM, Waldemar Horwat <[EMAIL PROTECTED]> wrote: > Sam Ruby wrote: >> On Fri, Aug 22, 2008 at 4:18 PM, Waldemar Horwat <[EMAIL PROTECTED]> wrote: >>> Sam Ruby wrote: >>>> On Fri, Aug 22, 2008 at 3:55 PM, Waldemar Horwat <[EMAIL PROTECTED]> wrote: >>>>> Here's a question for you: >>>>> >>>>> What should the full result of converting 1.1 to a Decimal be in >>>>> ECMAScript? Describe the precise answer and justify your choice of >>>>> answer. Hint: This would behave remarkably differently depending on >>>>> whether we settle on Decimal64 or Decimal128. >>>> At the present time, I am only suggesting that ECMAScript support >>>> Decimal128, and that there not by *any* implicit conversions to >>>> Decimal. >>>> >>>> Decimal.parse(n) would take n.ToString() and then parse that as a >>>> Decimal128 value. If (in the future) additional precisions were >>>> allowed by the standard, then there would be a second parameter on >>>> Decimal.parse that would allow the precision to be specified. >>>> Meanwhile: >>>> >>>> true: Decimal.parse(1.1) == 1.1m >>> An interesting choice. This produces more sensible results but directly >>> violates IEEE P754 section 5.3.3. >> >> I'm looking at DRAFT P754, April 24, 2008. Section 5.3.3 in this >> draft is entitled "logBFormat operations". I doubt that's what you >> are referring to. Can you provide me with a bit more context? > > Sorry, I meant 5.4.2.
I still don't see the conflict. If we desire, we can provide multiple mechanisms for converting binary64 floating point numbers to decimal128 floating point numbers. At a minimum, we should provide an analog to ES's existing parseFloat. I'd suggest that it be named Decimal.parse instead, and that it make use of decimal128-convertFromDecimalCharacter. >>> If we're using Decimal64, then there are no major issues. Converting 1.1 >>> do decimal would produce 1.1m, as both you and I desire. >>> >>> If we're using Decimal128, then IEEE P754 mandates that binary floats be >>> convertible to decimal floats and that the result of the conversion of 1.1 >>> to decimal be 1.100000000000000088817841970012523m. >>> >>> Hence, a dilemma if we choose Decimal128. Do we obey the standard? >> >> Deviations from the standard merit bug reports. > > Are you saying this is a bug in IEEE P754? I doubt it. I guess I was unclear. Places where draft ES3.1 deviate from IEEE P754 merits bug reports -- on ES3.1. > Waldemar > _______________________________________________ > Es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > _______________________________________________ Es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
