---------- Forwarded message --------- From: guest271314 <guest271...@gmail.com> Date: Tue, Mar 12, 2019 at 4:19 PM Subject: Re: Proposal: 1) Number (integer or decimal) to Array 2) Array to Number (integer or decimal) To: J Decker <d3c...@gmail.com>
So given that you can't convert to and from a number, I'm sure everyone is > having a problem knowing how this conversion would work for useful work. Which code are you using? Posted proof of concept, which had at least two bugs, and the answer to the question posted at Stack Overflow which fixed the bugs. The input and output that you posted input: 100.00015, > array: [ 1, 0, 0, 0.0001, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 9, 7, 9, 5 > ], araytoNum 100.05010000000497 is not consistent with the code posted by Shidersz <https://stackoverflow.com/users/10366495/shidersz>, which is also included at the OP var n = numberToArray(100.00015); // [1, 0, 0, 0.0001, 5] (expected output) arrayToNumber(n) // 100.00015 (expected output) On Tue, Mar 12, 2019 at 12:04 PM J Decker <d3c...@gmail.com> wrote: > The original code posted is not debugged. > > input: 100.00015, > array: [ 1, 0, 0, 0.0001, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 9, 7, 9, 5 > ], > araytoNum 100.05010000000497, > > So given that you can't convert to and from a number, I'm sure everyone is > having a problem knowing how this conversion would work for useful work. > { tests: > [ 0, > 200, > 100.00015, > -123, > 4.4, > 44.44, > -0.01, > 123, > 2.718281828459, > 321.7000000001, > 809.56, > 1.61803398874989, > 1.999, > 100.01, > 545454.45, > -7, > -83.782, > 12, > 1.5, > 100.0001 ], > arrays: > [ [ 0 ], > [ 2, 0, 0 ], > [ 1, 0, 0, 0.0001, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 9, 7, 9, 5 ], > [ -1, -2, -3 ], > [ 4, 0.4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4 ], > [ 4, 4, 0.4, 3, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 6 ], > [ -0.01 ], > [ 1, 2, 3 ], > [ 2, 0.7000000000000001, 1, 8, 2, 8, 1, 8, 2, 8, 4, 5, 8, 9, 9, 9, 8 > ], > [ 3, 2, 1, 0.7000000000000001, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 9, 9, 7, > 6, 1 ], > [ 8, 0, 9, 0.5, 5, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 4, 5, 4 ], > [ 1, 0.6000000000000001, 1, 8, 0, 3, 3, 9, 8, 8, 7, 4, 9, 8, 9, 0, 1 > ], > [ 1, 0.9, 9, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2 ], > [ 1, 0, 0, 0.01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 1, 1, 2 ], > [ 5, 4, 5, 4, 5, 4, 0.4, 4, 9, 9, 9, 9, 9, 9, 9, 9, 5, 3, 4, 3, 3, 9 > ], > [ -7 ], > [ -8, > -3, > -6.999999999999999e-16, > -8, > -1, > -9, > -9, > -9, > -9, > -9, > -9, > -9, > -9, > -9, > -9, > -9, > -6, > -2 ], > [ 1, 2 ], > [ 1, 0.5 ], > [ 1, 0, 0, 0.0001, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 3, 1, 9, 6, 4 ] ], > numbers: > [ 0, > 200, > 100.05010000000497, > -123, > 4.4, > 44.44, > -0.01, > 123, > 2.718281828459, > 321.7000000001, > 809.56, > 1.6180339887498902, > 1.999, > 100.01000000000005, > 545454.45, > -7, > -83.082, > 12, > 1.5, > 100.00010000000331 ] } > > > On Mon, Mar 11, 2019 at 11:13 PM guest271314 <guest271...@gmail.com> > wrote: > >> With respect, it's still not clear how you want to interact with the >>> array of values once you've destructured a Float into your array format. >> >> If all you have is an array of single-digit numbers that represent the >>> values in the tenths/hundredths/etc. positions of the source number, how >>> does this actually circumvent the challenges of representing Decimal values >>> that aren't exactly representable as a Float? >> >> >> It is not clear how your examples of adding specific values in JavaScript >> are relevant to the proposal. >> >> All of the test cases used at the code which fixed the bugs in the proof >> of concept at the original post output the expected result. >> >> If you have more test cases, number or decimal, to suggest for input >> relevant to the code at the original proposal, number to array, array to >> number, kindly post those tests cases listing input and expected output. >> >> The proposal does not seek to solve all JavaScript number issues. >> >> The proposal seeks to standardize the naming conventions of number to >> array and array to number, including decimals. An array is the simplest >> form of structured output. An object of key, value pairs (similar to >> Intl.NumberFormat, with JavaScript numbers instead of strings) can also be >> utilized for each of the digits of integer and decimal (fraction), if any. >> >> >> >> On Mon, Mar 11, 2019 at 4:33 PM Jeremy Martin <jmar...@gmail.com> wrote: >> >>> With respect, it's still not clear how you want to interact with the >>> array of values once you've destructured a Float into your array format. >>> >>> If all you have is an array of single-digit numbers that represent the >>> values in the tenths/hundredths/etc. positions of the source number, how >>> does this actually circumvent the challenges of representing Decimal values >>> that aren't exactly representable as a Float? >>> >>> To illustrate this challenge, let's use the classic example we've all >>> seen hundreds of times: >>> >>> > .1 + .2 >>> 0.30000000000000004 >>> >>> For a long time, all the reading I would do about *why* this produced a >>> weird result would *sort* of make sense and *sort* of confuse me. That >>> is, I could understand *why* 3/10ths isn't representable as a Float, >>> but then I would get confused by the fact that I could type `.3` into a >>> REPL, and it would *actually work *(??!): >>> >>> > .3 >>> 0.3 >>> >>> I mean, who's lying? How come `.3` works fine when I just type it >>> straight in, and `.1 + .3` works just fine, but there's just these >>> specific cases like `.1 + .2` where all of a sudden `.3` decides not to >>> be representable again? >>> >>> I admit this is conjecture, but maybe that's part of the confusion >>> motivating this proposal? And maybe the idea is that if we can break `.1` >>> and `.2` into some sort of an array structure (e.g., [0, 1] and [0, 2]), >>> then >>> we can add the individual parts as integers (giving us something like [0, >>> 3]) which we can then just convert back into a single numeric value at >>> the end as 0.3, and voila, no 0.30000000000000004 shenanigans? >>> >>> The problem is that this all builds on a fundamental misunderstanding of >>> what's going. Let's revisit the basic example of entering a value into the >>> REPL: >>> >>> > .3 >>> 0.3 >>> >>> This, as I stated earlier, contributed greatly to my own hangups in >>> understanding what was going on here. What I personally didn't understand >>> was that the `0.3` value you see above isn't actually the *Decimal* >>> value 0.3. It's just a *very* close approximation of 0.3. (so close, in >>> fact, that 0.3 is the *closest* Decimal value that it can be rounded >>> to, so that's what gets emitted). >>> >>> So, going back to our earlier example, why do we get a *different* >>> output when we're dealing with the result of a mathematical operation, as >>> opposed to getting the *same* very close approximation of 0.3 that we >>> get when we simply type it into the REPL? >>> >>> > .1 + .2 >>> 0.30000000000000004 >>> >>> The answer lies in the fact that 0.1 and 0.2 *also* can't be >>> represented exactly as Floats. Just like we saw with 0.3, we can type them >>> into the REPL and see a value that looks the exact same being emitted back >>> at us: >>> >>> > .1 >>> 0.1 >>> > .2 >>> 0.2 >>> >>> ...but also like we saw with 0.3, they only *look* like accurate >>> representations. Once again, 0.1 and 0.2 are just the closest Decimal >>> values that the underlying Float values can be rounded to for display. >>> >>> This rounding behavior, then, is what causes us to get >>> 0.30000000000000004 when we add them together, because the *slight* >>> rounding error with 0.1 and the *slight* rounding error with 0.2 >>> compound to result in a Float that no longer rounds closer to 0.3, and >>> instead closer to the "wrong" Decimal value that we see emitted before. >>> >>> It's worth noting that this same behavior applies to, e.g., 0.1 + 0.3, even >>> though that *looks* like it produces the correct result of 0.4. In >>> reality, however, this is just a case where the rounding errors have the >>> effect of (almost) canceling each other out, such that the resulting Float >>> rounds closer to 0.4 than any other value for display purposes (despite >>> being only negligibly more accurate than our 0.30000000000000004 result >>> was). >>> >>> Ok, so why am I trying to explain all this? Because I'm trying to >>> illustrate why it sounds like this proposal doesn't actually solve the >>> problem that you want it to. Is it possible to standardize a system for >>> transformations and math operations like the following? >>> >>> const arg1 = numberToArray(0.1) // [0, 1] >>> const arg2 = numberToArray(0.2) // [0, 2] >>> >>> const arraySum = addArrayNumbers(arg1, arg2) // [0, 3] >>> >>> const result = arrayToNumber(arraySum) // 0.3 >>> >>> Sure, and at the very end, you actually get a value that *looks* right ( >>> 0.3, yay!). But *it's still not actually 0.3.* So what become the >>> motivation for this? You have a solution that, in terms of memory and CPU >>> cycles, is orders of magnitude more costly to calculate than `0.1 + 0.2` as >>> a plain JavaScript expression, and in return you get a result that is, *at >>> best*, infinitesimally more accurate than the alternative when carried >>> all the way out to the quadrillionths place or greater. >>> >>> Do you actually have a use case for mathematical operations that are >>> fault tolerant enough to represent Decimal values as Floats, but that fault >>> tolerance is sensitive to very, very specific rounding behavior at the >>> quadrillionths level? I can't even imagine what that use case would be. >>> >>> On Mon, Mar 11, 2019 at 10:06 AM guest271314 <guest271...@gmail.com> >>> wrote: >>> >>>> JS numbers are specified to be in terms of IEEE-754 doubles, so tenths, >>>>> hundredths, and so on cannot be precisely represented. [1] So there is no >>>>> way to increase precision here beyond the above that Tab showed, assuming >>>>> each of those operations are accurate to the bit. >>>> >>>> >>>> Not sure what the message is trying to convey? The code at the first >>>> post already overcomes the issue of >>>> >>>> i % 1 // 0.5670000000000073 >>>> >>>> described by Tab. All of the input numbers are converted to array then >>>> back to number without losing any precision or adding more numbers to the >>>> input. >>>> >>>> The proposal suggests that each discrete digit of any number a user can >>>> get and set and be clearly defined with a consistent name, or reference. >>>> Converting the number to an array is a simple means of processing each >>>> digit independently. >>>> >>>> On Mon, Mar 11, 2019 at 10:41 AM Isiah Meadows <isiahmead...@gmail.com> >>>> wrote: >>>> >>>>> JS numbers are specified to be in terms of IEEE-754 doubles, so >>>>> tenths, hundredths, and so on cannot be precisely represented. [1] So >>>>> there >>>>> is no way to increase precision here beyond the above that Tab showed, >>>>> assuming each of those operations are accurate to the bit. >>>>> >>>>> [1]: >>>>> https://www.exploringbinary.com/why-0-point-1-does-not-exist-in-floating-point/ >>>>> On Sun, Mar 10, 2019 at 13:26 guest271314 <guest271...@gmail.com> >>>>> wrote: >>>>> >>>>>> So this would help with precision? >>>>>> >>>>>> >>>>>> To an appreciable degree, yes, without the scope of JavaScript >>>>>> floating-point number implementation. >>>>>> >>>>>> The gist of the proposal is to formalize, standardize, or whatever >>>>>> term specification writers want to use, the *naming* of each method or >>>>>> operation which can get and set each discrete digit of a number - without >>>>>> using String methods. >>>>>> >>>>>> For input >>>>>> >>>>>> 1234.567 >>>>>> >>>>>> Each digit has a formal name which developers can get and set, >>>>>> whether in an array, object or number format. >>>>>> >>>>>> On Sun, Mar 10, 2019 at 5:17 PM Michael Theriot < >>>>>> michael.lee.ther...@gmail.com> wrote: >>>>>> >>>>>>> So this would help with precision? >>>>>>> >>>>>>> On Sunday, March 10, 2019, guest271314 <guest271...@gmail.com> >>>>>>> wrote: >>>>>>> >>>>>>>> (If you really wanted this as an integer, it's not well-founded; >>>>>>>>> .567 >>>>>>>>> isn't exactly representable as a double, so JS doesn't know that >>>>>>>>> you >>>>>>>>> "meant" it to have only three digits after the decimal point, and >>>>>>>>> thus >>>>>>>>> want 567 as the answer. You'll instead get some very very large >>>>>>>>> integer that *starts with* 567, followed by a bunch of zeros, >>>>>>>>> followed >>>>>>>>> by some randomish digits at the end.) >>>>>>>> >>>>>>>> >>>>>>>> The code at the first post solves that problem. >>>>>>>> >>>>>>>> But the question is still "what would someone use this information >>>>>>>>> for?" >>>>>>>> >>>>>>>> >>>>>>>> That question has been answered several times in the posts above. >>>>>>>> This users' motivation was and is the ability to manipulate JavaScript >>>>>>>> floating-point numbers (which could be considered "broken", as you >>>>>>>> described above) in order to solve mathematical problems (in this case, >>>>>>>> directly calculating the *n*th lexicographic permutation) with the >>>>>>>> number or decimal being represented as an array, without having to be >>>>>>>> concerned with not getting the same value when the array is converted >>>>>>>> back >>>>>>>> to a number. >>>>>>>> >>>>>>>> Felipe Nascimento de Moura mentioned several other applications. >>>>>>>> >>>>>>>> The work has already been done. This proposal is essentially to >>>>>>>> standardize the naming conventions. Whether a Number method is used >>>>>>>> >>>>>>>> i.getTensMethod >>>>>>>> >>>>>>>> or an array is used >>>>>>>> >>>>>>>> arr["integer"] // 1234 >>>>>>>> >>>>>>>> or an object where values are arrays is used >>>>>>>> >>>>>>>> o["fraction"] // .567 >>>>>>>> >>>>>>>> Having mentioned Intl.NumberFormat earlier in the thread, if the >>>>>>>> issue devoting resources to a *new *proposal, Intl.NumberFormate >>>>>>>> can be extended; e.g. a rough draft in code >>>>>>>> >>>>>>>> function formatNumberParts(args) { >>>>>>>> return Object.assign({sign:0, fraction:[0], integer:[0]}, >>>>>>>> ...args.filter(({type}) => type === "integer" || type === "fraction" || >>>>>>>> type === "minusSign").map(({type, value}) => ({[type === "minusSign" ? >>>>>>>> "sign" : type]: type !== "minusSign" ? [...value].map(Number) : -1}))); >>>>>>>> } >>>>>>>> >>>>>>>> let number = -123; >>>>>>>> >>>>>>>> let formatter = new Intl.NumberFormat('en-US'); >>>>>>>> >>>>>>>> let res = formatter.formatToParts(number); >>>>>>>> >>>>>>>> formatNumberParts(res); >>>>>>>> >>>>>>>> If the concern is that the proposal would not be useful, consider >>>>>>>> what you would *name* various uses of Math.trunc and remainder >>>>>>>> operator used at your message? >>>>>>>> >>>>>>>> >>>>>>>> On Sun, Mar 10, 2019 at 3:58 PM Tab Atkins Jr. < >>>>>>>> jackalm...@gmail.com> wrote: >>>>>>>> >>>>>>>>> On Sat, Mar 9, 2019 at 11:10 AM Felipe Nascimento de Moura >>>>>>>>> <felipenmo...@gmail.com> wrote: >>>>>>>>> > >>>>>>>>> > Personally, I don't think it would be THAT useful... >>>>>>>>> > but...I think there is something behind this proposal that makes >>>>>>>>> sense. >>>>>>>>> > >>>>>>>>> > I do believe it could be useful for developers to have an easier >>>>>>>>> access to number parts or characteristics. >>>>>>>>> > Perhaps something like: >>>>>>>>> > >>>>>>>>> > const i = 1234.567; >>>>>>>>> >>>>>>>>> Can you provide a scenario in which these would do something >>>>>>>>> useful, >>>>>>>>> such that it would be worth adding them over just using the math >>>>>>>>> operations that already exist? >>>>>>>>> >>>>>>>>> > console.log( i.float ); // 567 >>>>>>>>> >>>>>>>>> i % 1 >>>>>>>>> >>>>>>>>> (If you really wanted this as an integer, it's not well-founded; >>>>>>>>> .567 >>>>>>>>> isn't exactly representable as a double, so JS doesn't know that >>>>>>>>> you >>>>>>>>> "meant" it to have only three digits after the decimal point, and >>>>>>>>> thus >>>>>>>>> want 567 as the answer. You'll instead get some very very large >>>>>>>>> integer that *starts with* 567, followed by a bunch of zeros, >>>>>>>>> followed >>>>>>>>> by some randomish digits at the end.) >>>>>>>>> >>>>>>>>> > console.log( i.abs ); // 1234 >>>>>>>>> >>>>>>>>> Math.trunc(i) >>>>>>>>> >>>>>>>>> > console.log( i.thousands ); // 1 >>>>>>>>> >>>>>>>>> Math.trunc(i / 1000) >>>>>>>>> >>>>>>>>> > console.log( i.million ); // 0 >>>>>>>>> >>>>>>>>> Math.trunc(i / 1e6) >>>>>>>>> >>>>>>>>> > console.log( i.hundred ); // 2 >>>>>>>>> >>>>>>>>> Math.trunc(i / 100) % 10 >>>>>>>>> >>>>>>>>> > console.log( i.hundreds ); // 12 >>>>>>>>> >>>>>>>>> Math.trunc(i / 100) >>>>>>>>> >>>>>>>>> > console.log( i.ten ); // 2 >>>>>>>>> >>>>>>>>> Math.trunc(i / 10) % 10 >>>>>>>>> >>>>>>>>> > console.log( i.tens ); // 123 >>>>>>>>> >>>>>>>>> Math.trunc(i / 10) >>>>>>>>> >>>>>>>>> > console.log( i.tenth ); // 5 >>>>>>>>> >>>>>>>>> Math.trunc(i % 1 * 10) % 10 >>>>>>>>> >>>>>>>>> > console.log( i.tenths ); // 5 >>>>>>>>> >>>>>>>>> Math.trunc(i % 1 * 10) >>>>>>>>> >>>>>>>>> > console.log( i.hundredth ); // 6 >>>>>>>>> >>>>>>>>> Math.trunc(i % 1 * 100) % 10 >>>>>>>>> >>>>>>>>> > console.log( i.hundredths ); // 56 >>>>>>>>> >>>>>>>>> Math.trunc(i % 1 * 100) >>>>>>>>> >>>>>>>>> >>>>>>>>> Some of these are easy to remember and use; others take some >>>>>>>>> thinking >>>>>>>>> to deploy. But the question is still "what would someone use this >>>>>>>>> information for?", such that the benefit to developers is worth the >>>>>>>>> cost to all parties involved (spec writers, implementors, testers, >>>>>>>>> and >>>>>>>>> then developers having to navigate a larger stdlib). >>>>>>>>> >>>>>>>>> ~TJ >>>>>>>>> _______________________________________________ >>>>>>>>> es-discuss mailing list >>>>>>>>> es-discuss@mozilla.org >>>>>>>>> https://mail.mozilla.org/listinfo/es-discuss >>>>>>>>> >>>>>>>> _______________________________________________ >>>>>>> es-discuss mailing list >>>>>>> es-discuss@mozilla.org >>>>>>> https://mail.mozilla.org/listinfo/es-discuss >>>>>>> >>>>>> _______________________________________________ >>>>>> es-discuss mailing list >>>>>> es-discuss@mozilla.org >>>>>> https://mail.mozilla.org/listinfo/es-discuss >>>>>> >>>>> _______________________________________________ >>>> es-discuss mailing list >>>> es-discuss@mozilla.org >>>> https://mail.mozilla.org/listinfo/es-discuss >>>> >>> >>> >>> -- >>> Jeremy Martin >>> 661.312.3853 >>> @jmar777 <https://twitter.com/jmar777> / @j <https://stream.live/j> >>> >>> _______________________________________________ >> es-discuss mailing list >> es-discuss@mozilla.org >> https://mail.mozilla.org/listinfo/es-discuss >> >
_______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
