Friends, you can lead a freshman to idea but you can't make him think. Sent from my iPad
On Feb 3, 2012, at 1:03 PM, Raul Miller <rauldmil...@gmail.com> wrote: > I liked the reference which Roger Hui posted: > http://www.jsoftware.com/papers/EvalOrder.htm which points out some of > the ambiguities in PEMDAS. > > -- > Raul > > On Fri, Feb 3, 2012 at 1:55 PM, Devon McCormick <devon...@gmail.com> wrote: >> You could also highlight the difference in complexity between the baroque - >> http://en.cppreference.com/w/cpp/language/operator_precedence - and the >> simple - "right to left". >> >> On Fri, Feb 3, 2012 at 1:19 PM, Roger Hui <rogerhui.can...@gmail.com> wrote: >> >>> You can point out that when there are 100 functions a hierarchy like that >>> is unwieldy. See also Ken's paper from 1966, *Conventions governing order >>> of evaluation* <http://www.jsoftware.com/papers/EvalOrder.htm>. >>> >>> <http://www.jsoftware.com/papers/EvalOrder.htm> >>> >>> On Fri, Feb 3, 2012 at 9:24 AM, km <k...@math.uh.edu> wrote: >>> >>>> A big problem for college freshmen is that calculators tell them 2*3+4 is >>>> 10 and J tells them 14. With apologies to "South Pacific": they have >>> been >>>> carefully taught PEMDAS. >>>> >>>> Sent from my iPad >>>> >>>> >>>> On Feb 3, 2012, at 10:44 AM, Michael Dykman <mdyk...@gmail.com> wrote: >>>> >>>>> This may sound trite, but >>>>> >>>>> Who is the audience? Everyone who does math, be it for engineering, >>>>> finance, or middle-school algebra. Interactive J should be >>>>> approachable for a 10 year-old and would be a huge improvement over >>>>> the calculators and spreadsheets in current use. >>>>> >>>>> What do they already know about J? Nothing or less. While I am >>>>> occasionally surprised by the extent that J is used among very senior >>>>> financial types, it is a fact that J remains deep in obscurity within >>>>> the IT industry. I can't imagine that the picture is any clearer among >>>>> educators. >>>>> >>>>> What the want to know is how to do basic math with the console. What >>>>> they need is enough of a foundation to begin exploring complex >>>>> relationships. >>>>> >>>>> I agree, Khan Academy provides an excellent model. If we (as a >>>>> community) were ever fortunate enough to have Khan produce some >>>>> introductory materials, usage would explode. >>>>> >>>>> Having said that, shouldn't this thread be migrated to Chat? >>>>> >>>>> - michael dykman >>>>> >>>>> On Fri, Feb 3, 2012 at 11:02 AM, Dan Bron <j...@bron.us> wrote: >>>>>> Hmm. I could do a basic intro to J course at one of the NYC JUGs. If >>>> we >>>>>> broadcast & record it, we could then post it on youtube. >>>>>> >>>>>> The question is: who is the audience? What do they already know about >>>> J? >>>>>> What do they want to know? >>>>>> >>>>>> -Dan >>>>>> >>>>>> -----Original Message----- >>>>>> From: programming-boun...@jsoftware.com >>>>>> [mailto:programming-boun...@jsoftware.com] On Behalf Of William >>>> Tanksley, Jr >>>>>> Sent: Friday, February 03, 2012 10:43 AM >>>>>> To: Programming forum >>>>>> Subject: Re: [Jprogramming] Demise of @ and [: debate >>>>>> >>>>>> I'd love to see a youtube class on J. I'd download every episode as it >>>>>> aired to my phone and watch it on the train, using my computer to do >>>>>> experiments and take notes. That's what I do with "njwilberger" >>>>>> rational trig and hyperbolic geometry lessons. >>>>>> >>>>>> -Wm >>>>>> >>>>>> On Fri, Feb 3, 2012 at 6:57 AM, Skip Cave <s...@caveconsulting.com> >>>> wrote: >>>>>>> A methodical approach to teaching J might be to group the primitives >>>> into >>>>>>> groups of similar functionality. Order these groups by complexity >>>> (simple >>>>>>> to complex), as well as perhaps ranking them by familiarity with >>>>>>> already-learned concepts from traditional math classes, most familiar >>>>>>> first. >>>>>>> >>>>>>> With a learning sequence defined, spend a class on each group of >>>>>>> primitives, starting with the simplest and most familiar functions >>>> (+-*%, >>>>>>> or perhaps = =. =:), and progress to the most complex and unfamiliar >>>>>>> functions.You should probably start with direct execution, and >>>> introduce >>>>>>> verb creation after a few classes on basic primitives. Some class >>> time >>>>>>> should be spent on how to read and understand the vocabulary >>>> definitions. >>>>>>> >>>>>>> Homework for each class would focus on usage of that current classes' >>>>>>> primitives, with previously-covered primitives thrown in for good >>>> measure. >>>>>>> The homework problems should be constructed to not require primitives >>>> that >>>>>>> haven't been covered yet (though nothing would prevent an advanced >>>> student >>>>>>> from looking ahead and trying them). >>>>>>> >>>>>>> It would be interesting to create an online J class, much like the >>> Khan >>>>>>> Academy on youtube. In fact, if you really wanted to introduce J to >>> the >>>>>>> masses, create a math tutorial that follows and supports Khan's math >>>>>>> tutorials, using J as the tool. This would be similar to Iverson's >>>>>>> "Concrete Math Companion" which follows 'Concrete Mathematics' >>> (Graham, >>>>>>> Knuth, and Patashnik (GKP)). >>>>>>> >>>>>>> Just a thought.. >>>>>>> >>>>>>> Skip >>>>>>> >>>>>>> >>>>>>> On Fri, Feb 3, 2012 at 2:27 AM, Linda Alvord >>>>>> <lindaalv...@verizon.net>wrote: >>>>>>> >>>>>>>> I agree, Don. I really was using a post from Roger because I find >>> his >>>> the >>>>>>>> most difficult to untangle. This thread was a good one to explain my >>>> new >>>>>>>> thoughts about @ and [: >>>>>>>> >>>>>>>> My challenges are topics I might use to teach high school seniors >>>>>> studying >>>>>>>> precalculus, probability and statistics. They are similar to old APL >>>>>>>> contests I invented while I was teaching APL - to get better with >>> the >>>>>>>> language myself. However, I'm not sure what would work in classes >>>> these >>>>>>>> days. >>>>>>>> >>>>>>>> At least I'm having fun with the readers of the forum. J is even >>>> becoming >>>>>>>> fun to use! >>>>>>>> >>>>>>>> Linda >>>>>>>> >>>>>>>> -----Original Message----- >>>>>>>> From: programming-boun...@jsoftware.com >>>>>>>> [mailto:programming-boun...@jsoftware.com] On Behalf Of Don Guinn >>>>>>>> Sent: Friday, February 03, 2012 12:04 AM >>>>>>>> To: Programming forum >>>>>>>> Subject: Re: [Jprogramming] Understanding C. , A. >>>>>>>> >>>>>>>> Might want to get beginners a little comfortable with J before >>> showing >>>>>> them >>>>>>>> C. and A. >>>>>>>> >>>>>>>> On Thu, Feb 2, 2012 at 7:56 PM, Linda Alvord < >>> lindaalv...@verizon.net >>>>>>>>> wrote: >>>>>>>> >>>>>>>>> I am rethinking my concern with @ and [: and am leaning toward >>>>>> using >>>>>>>>> explicit definitions as a way of teaching J to beginners as a >>>> natural >>>>>>>>> mathematical language. >>>>>>>>> >>>>>>>>> Some of the programmers responding to the forum think in idioms and >>>> use >>>>>>>> @ >>>>>>>>> happily. >>>>>>>>> >>>>>>>>> f >>>>>>>>> <:@-@[ C.&.|. ] >>>>>>>>> i >>>>>>>>> -@#@[ |. C. >>>>>>>>> k >>>>>>>>> <@i.@-@>:@[ C. ] >>>>>>>>> >>>>>>>>> 0thers favor the tacit approach with lots of [: >>>>>>>>> >>>>>>>>> g >>>>>>>>> ] C.&.|.~ [: <: [: - [ >>>>>>>>> h >>>>>>>>> [: |. ([: <: [: - [) C. [: |. ] >>>>>>>>> j >>>>>>>>> C. |.~ [: - [: # [ >>>>>>>>> >>>>>>>>> >>>>>>>>> Both styles are appropriate and I should not suggest one way or the >>>>>>>> other. >>>>>>>>> Many of you have suggested this. >>>>>>>>> >>>>>>>>> >>>>>>>>> We are looking for a simple way to introduce J to beginners. In >>> my >>>>>>>>> opinion >>>>>>>>> we would introduce J as a mathematical language for solving >>> problem. >>>>>>>>> >>>>>>>>> >>>>>>>>> I am suggest starting with expressions that produce desired >>> results. >>>>>>>>> Developing from right to left may come naturally. >>>>>>>>> >>>>>>>>> (<:-3 6)C.&.|.'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> >>>>>>>>> The next step is making explicit functions indicating if the >>> intended >>>>>> use >>>>>>>>> is >>>>>>>>> monadic or dyadic. There is no use of @ or [: allowed at this >>>> point. >>>>>>>>> >>>>>>>>> g=: 13 :'(<:-x)C.&.|.y' >>>>>>>>> h=: 13 :'|.(<:-x)C.|.y' >>>>>>>>> j=: 13 :'(-#x)|.x C.y' >>>>>>>>> >>>>>>>>> Now exploring the tacit definitions would be appropriate in some >>>>>>>>> environments and can be explored an studied in terms of forks and >>>>>> hooks. >>>>>>>>> At this special code and common idioms can be explored and timing >>> of >>>>>>>>> expressions can be compared. In the end all roads lead to Rome. >>>>>>>>> >>>>>>>>> 3 6 f 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> 3 6 g 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> 3 6 h 'abc*ef*g't >>>>>>>>> **abcefg >>>>>>>>> 3 6 i 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> 3 6 j 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> >>>>>>>>> >>>>>>>>> -----Original Message----- >>>>>>>>> From: programming-boun...@jsoftware.com >>>>>>>>> [mailto:programming-boun...@jsoftware.com] On Behalf Of Linda >>> Alvord >>>>>>>>> Sent: Wednesday, February 01, 2012 6:01 PM >>>>>>>>> To: 'Programming forum' >>>>>>>>> Subject: Re: [Jprogramming] Understanding C. , A. >>>>>>>>> >>>>>>>>> Sorry I missed the version by Arie. Nice! >>>>>>>>> >>>>>>>>> 3 6 (i=:-@#@[ |. C.) 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> i >>>>>>>>> -@#@[ |. C. >>>>>>>>> >>>>>>>>> j=: 13 :'(-#x)|.x C.y' >>>>>>>>> j >>>>>>>>> C. |.~ [: - [: # [ >>>>>>>>> >>>>>>>>> 3 6 j 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> >>>>>>>>> Please let me know if you have concerns or modifications as I plan >>> to >>>>>> use >>>>>>>>> different rules beginning with challenge 6. >>>>>>>>> >>>>>>>>> Henceforth I'll have no opinion concerning the merits of @ and >>> [: >>>> I >>>>>>>>> hope >>>>>>>>> to learn to favor them both gracefully. >>>>>>>>> >>>>>>>>> Linda >>>>>>>>> >>>>>>>>> -----Original Message----- >>>>>>>>> From: programming-boun...@jsoftware.com >>>>>>>>> [mailto:programming-boun...@jsoftware.com] On Behalf Of Linda >>> Alvord >>>>>>>>> Sent: Wednesday, February 01, 2012 5:20 PM >>>>>>>>> To: 'Programming forum' >>>>>>>>> Subject: Re: [Jprogramming] Understanding C. , A. >>>>>>>>> >>>>>>>>> I'm happiest with the explicit version. It shows the arguments >>> needed >>>>>> for >>>>>>>>> the application. >>>>>>>>> >>>>>>>>> 3 6 (f=:<:@-@[ C.&.|. ]) 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> 3 6 f a=:'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> >>>>>>>>> g=: 13 :'(<:-x)C.&.|.y'! >>>>>>>>> 3 6 g a >>>>>>>>> **abcefg >>>>>>>>> >>>>>>>>> f >>>>>>>>> <:@-@[ C.&.|. ] >>>>>>>>> g >>>>>>>>> ] C.&.|.~ [: <: [: - [ >>>>>>>>> g=: 13 :'(<:-x)C.&.|.y' >>>>>>>>> >>>>>>>>> J provides the ~ which shows up in the tacit version above. >>>>>>>>> >>>>>>>>> Then there is h with no ~ and no &. >>>>>>>>> >>>>>>>>> h=: 13 :'|.(<:-x)C.|.y' >>>>>>>>> h >>>>>>>>> [: |. ([: <: [: - [) C. [: |. ] >>>>>>>>> 3 6 h a >>>>>>>>> **abcefg >>>>>>>>> >>>>>>>>> Linda >>>>>>>>> >>>>>>>>> >>>>>>>>> -----Original Message----- >>>>>>>>> From: programming-boun...@jsoftware.com >>>>>>>>> [mailto:programming-boun...@jsoftware.com] On Behalf Of Roger Hui >>>>>>>>> Sent: Wednesday, February 01, 2012 11:26 AM >>>>>>>>> To: Programming forum >>>>>>>>> Subject: Re: [Jprogramming] Understanding C. , A. >>>>>>>>> >>>>>>>>> Personally, I dislike expressions with multiple uses of ~ as they >>>> make >>>>>> my >>>>>>>>> head spin. >>>>>>>>> >>>>>>>>> 3 6 (C.&.|.~ <:@-)~ 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> 3 6 (<:@-@[ C.&.|. ]) 'abc*ef*g' >>>>>>>>> **abcefg >>>>>>>>> >>>>>>>>> I much prefer the second over the first. >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Wed, Feb 1, 2012 at 8:05 AM, Aai <agroeneveld...@gmail.com> >>>> wrote: >>>>>>>>> >>>>>>>>>> Ah, I see that's a bit like yours David. >>>>>>>>>> >>>>>>>>>> Modifying it for 1< #x >>>>>>>>>> >>>>>>>>>> 3 6 (C. |.~ -@#@[) 'abc*ef*g' >>>>>>>>>> **abcefg >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> (from Essays) >>>>>>>>>> >>>>>>>>>> 3 6 (C.&.|.~ <:@-)~ 'abc*ef*g' >>>>>>>>>> **abcefg >>>>>>>>>> k >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On 01-02-12 16:47, Aai wrote: >>>>>>>>>>> Sorry for the noise. You should forget the previous ones I sent: >>>>>> they >>>>>>>>>>> are wrong. >>>>>>>>>>> >>>>>>>>>>> It looks like this one is ok: >>>>>>>>>>> >>>>>>>>>>> mtf=:_1&|.@C. >>>>>>>>>>> >>>>>>>>>>> ]samples=: '*abcef' |."0 1 ~-i.6 >>>>>>>>>>> *abcef >>>>>>>>>>> f*abce >>>>>>>>>>> ef*abc >>>>>>>>>>> cef*ab >>>>>>>>>>> bcef*a >>>>>>>>>>> abcef* >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> ]res=: '*' ([,-.~) "1 samples >>>>>>>>>>> *abcef >>>>>>>>>>> *fabce >>>>>>>>>>> *efabc >>>>>>>>>>> *cefab >>>>>>>>>>> *bcefa >>>>>>>>>>> *abcef >>>>>>>>>>> >>>>>>>>>>> res -: mtf&>/"1 (;~I.@:('*'&=))"1 samples >>>>>>>>>>> 1 >>>> >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >>> >> >> >> >> -- >> Devon McCormick, CFA >> ^me^ at acm. >> org is my >> preferred e-mail >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
