http://www.jsoftware.com/jwiki/JinaDay
Thanks to all for crits, and for provocative & instructive discussions. It doesn't escape me that a lot of people have really spent time to debug it. 1st draft done. Extensive edits. Most people's suggestions incorporated (I've not checked everyone's is in, but I will). Demo app CALC somewhat improved, behaviour more intuitive, focus problem hopefully solved. Correct (?) use of the term "array" -- which has proved useful after all. LOBROW will need some spit&polish before final publication. Ditto handy.ijs. Haven't checked that all weblinks are actually used in the text. On the other hand there may be more that ought to be mentioned. Virtually no mention of the J Primer, which IMO is an omission. Ian On Wed, Oct 27, 2010 at 12:08 AM, Ian Clark <[email protected]> wrote: > This all makes me think that JinaDay needs a section just on scalars: > their enormous power when combined with non-scalars. > > One of the things that blew me away when I first got to play with > extended APL was just that: the ability to box up almost anything -- > and it becomes a well-behaved scalar, which you can combine with a > vector or matrix (...with results you're able to predict). And complex > numbers and the power they lend in mathematical analysis is not to be > neglected here. Even just as a paradigm to expand on, for those who > understand them. > > I do not have the precision of [J] language to develop the topic > succintly. But anyway, even a short treatment may be too indigestible > for "fast-food" JinaDay. But including a TinyURL to a position paper > in the wiki is another matter entirely. Perhaps motivated by a juicy, > but not too highbrow, example. > > It may already exist in there, somewhere. If I was better at searching > the wiki / Dic / Voc etc, I might even find it. > > Be that as it may, if it is found / gets written, it'd be good to > impart to the newbie in JinaDay that it exists, and where s/he can > find it -- when s/he has the time&inclination to study it. > > Ian > > > On Tue, Oct 26, 2010 at 5:36 PM, Don Guinn <[email protected]> wrote: >> There are two issues here. One, which I was addressing, is how J internally >> handles nouns, which I would think is the way nouns should be taught if >> teaching J. >> >> In mathematical terms I would still think that a complex number is still a >> scalar. That a complex number is represented by a pair of rational numbers >> is in our notation. 3j4 for example. Likewise, when we express a rational >> number in scientific notation it is actually a pair of numbers separated by >> the letter "E". Would you call that a scalar or an array? Internally in the >> computer a floating point number is actually a pair of integers within a >> computer word. >> >> I suspect that "array" is another one of those terms like "operator" and >> "function" with ambiguous and conflicting definitions. Intuitively obvious? >> Some definitions exclude scalars. Others do not. >> >> >> >> On Tue, Oct 26, 2010 at 10:03 AM, Donna Y <[email protected]> wrote: >> >>> Sorry - I am thinking in terms of mathematics where a complex number or >>> Imaginary number is not a scalar >>> >>> numbers in an array have a position while a scalar is just a magnitude - >>> however it seems from what Roger is saying that all numbers in APL and J are >>> in arrays - there is no other way provided to express a scalar number >>> >>> Donna >>> [email protected] >>> >>> >>> On 2010-10-26, at 10:54 AM, Don Guinn wrote: >>> >>> > 3!:3]99j1 >>> > e1000000 >>> > 10000000 >>> > 01000000 >>> > 00000000 >>> > 00000000 >>> > 00c05840 >>> > 00000000 >>> > 0000f03f >>> > >>> > J still treats a complex number as a zero rank array. >>> > >>> > 3!:3]99r2 >>> > e1000000 >>> > 80000000 >>> > 01000000 >>> > 00000000 >>> > 18000000 >>> > 30000000 >>> > e1000000 >>> > 04000000 >>> > 01000000 >>> > 01000000 >>> > 01000000 >>> > 63000000 >>> > e1000000 >>> > 04000000 >>> > 01000000 >>> > 01000000 >>> > 01000000 >>> > 02000000 >>> > >>> > Same for rationals. >>> > >>> > On Tue, Oct 26, 2010 at 8:50 AM, Raul Miller <[email protected]> >>> wrote: >>> > >>> >> On Mon, Oct 25, 2010 at 9:34 PM, Donna Y <[email protected]> wrote: >>> >>> An array can have one element but it is not a scalar number. >>> >>> If it is an array it has not only magnitude but also direction. >>> >>> >>> >>> A scalar number by definition scales - it has magnitude - it >>> >>> is not a vector or an array. It has rank 0. >>> >> >>> >> I did not follow all of what you wrote, but consider: >>> >> >>> >> scalar: 1j2 (has magnitude and direction, and is an array) >>> >> array: i.0 1 2 3 4 (has no magnitudes and no directions, but still is >>> an >>> >> array) >>> >> >>> >> -- >>> >> Raul >>> >> ---------------------------------------------------------------------- >>> >> 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 >>> >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
