Hey Raul, The subject of my conference talk was going to be jsoftware.com as a learning ecology and labs are a big part of that (and could become bigger). I have not seen a specific lab author since J602. Do you know of one or are we following the "use any text editor" advice?
http://www.jsoftware.com/jwiki/Labs Cheers, bob On Apr 23, 2014, at 11:23 AM, Raul Miller <rauldmil...@gmail.com> wrote: > If you are interested, you might consider putting together a J lab on the > subject. > > This would: > > (a) Help you retain the concepts for yourself, and expand your > understanding of them, and > (b) Help convey them to other people, also. > > If this interests you, we can help point you at lab authoring > documentation. We need some people interested in writing some labs because > the new platforms (especially phones) have UI adaptations which need some > fixing, for labs. > > Meanwhile, one of the more important issues for an author is finding a good > reviewing audience to work with. (Even more important, of course, is > writing stuff.) > > Thanks, > > -- > Raul > > > On Wed, Apr 23, 2014 at 1:52 PM, alexgian <alexg...@blueyonder.co.uk> wrote: > >>> The information and more are in the vocabulary page for %. >> >> Well, yes, but so tersely and compactly expressed that you have to know the >> long answer before you understand it! I did look at the Vocab page, but >> didn't "get it", that's why I posted. >> >> It needed Roger's somewhat more expanded explanation for those of us that >> are somewhat slower on the uptake. That's why I said the Vocab could use a >> touch up. It is NOT user friendly, more of an ultra-coded reference. Of >> course, you might not see it this way, but I'd bet most newcomers would. >> >> And it's not as if there is a longer explanation somewhere else, is there? >> Well, other than this thread, I mean... :) >> >> >> >> On 23 April 2014 18:17, Roger Hui <rogerhui.can...@gmail.com> wrote: >> >>> The information and more are in the vocabulary page for %. >>> http://www.jsoftware.com/help/dictionary/d131.htm . >>> >>> >>> On Wed, Apr 23, 2014 at 10:02 AM, alexgian <alexg...@blueyonder.co.uk >>>> wrote: >>> >>>> Great info, thanks Roger. >>>> If it was up to me, I'd DEFINITELY include that in the Vocabulary, is >> it >>>> even documented anywhere else? >>>> >>>> >>>> On 23 April 2014 17:33, Roger Hui <rogerhui.can...@gmail.com> wrote: >>>> >>>>> %. x for a vector x is the same as ($x)$%.,.x, and the key expression >>> is >>>>> %.,.x, the "matrix inverse" of a 1-column matrix. b=.y%.x on a tall >>>> matrix >>>>> x is solving a least-squares problem, the coefficients b that >> minimizes >>>> the >>>>> sum of squares of y - x +/ .* b . >>>>> >>>>> In addition, for a non-zero vector x, (%.x) +/ .* x is 1, a special >>> case >>>> of >>>>> that (%.x)+/ .* x is an identity matrix, whence one can deduce that >> for >>>>> vector x, %.x is x%+/x^2. >>>>> >>>>> ] x=: 7 ?.@$ 100 >>>>> 94 56 8 6 85 48 66 >>>>> %. x >>>>> 0.00362137 0.00215741 0.000308202 0.000231152 0.00327465 0.00184921 >>>>> 0.00254267 >>>>> (%.x) +/ .* x >>>>> 1 >>>>> x % +/x^2 >>>>> 0.00362137 0.00215741 0.000308202 0.000231152 0.00327465 0.00184921 >>>>> 0.00254267 >>>>> >>>>> M=: 7 3 ?.@$ 100 >>>>> (%.M) +/ .* M >>>>> 1 5.55112e_17 _2.77556e_17 >>>>> _1.21431e_16 1 1.11022e_16 >>>>> _4.85723e_17 1.94289e_16 1 >>>>> >>>>> >>>>> >>>>> On Wed, Apr 23, 2014 at 9:13 AM, alexgian <alexg...@blueyonder.co.uk >>> >>>>> wrote: >>>>> >>>>>> Just wondering: >>>>>> %. 2 3 4 >>>>>> 0.0689655 0.103448 0.137931 >>>>>> >>>>>> Which is fair enough enough at one level, I suppose, since the dot >>>>> product >>>>>> of the two arrays IS 1, but what system/equation is being solved >>> here? >>>>>> Obviously, there are infinite solutions. Why that one? >>>>>> IOW, which "matrix" is being inverted here? >>>>>> >>>>>> Thanks >>>>>> >>> ---------------------------------------------------------------------- >>>>>> 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 >> > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
