Henry Rich wrote:
> I think I agree with all your statements, but you are not responding to
> my questions, which will help focus the discussion:
>
> 1. What is a Dictionary, EXACTLY?
FWIW, I find myself confused by this question.
Maybe I am just failing to pick up on an implicit convention
Henry Rich wrote:
> RE: #:, with multiple dots, creates a list. #. creates an atom.
Yeah, AFAICT there's not really a "system" to the dot usage, per se, so much as
an art:
". converts into a (single) number/array
": splits into (multiple) boxes
|. works on the lower level, i.e.
FWIW, this alternate phrasing of the rt verb is also possible.
rt=: (%: -)~ * ^@(%~ 0j1p1+0j2p1*i.)@]
Elijah Stone wrote:
> - is always a verb, which negates its right argument. -1 0 1 is - (1 0
> 1), or _1 0 _1; so p. solves -x^2 - 1 = 0. I expect you want _1 0 1.
>
> -E
>
> On Sun,
Henry Rich wrote:
> Offset binary.
>
> /:~&.(22 b.&16b8000)
>
Cute! But I think the mask needs to be negative. INT_MAX is all f's.
/:~&.(22 b.&16b8000) i:10
_1 _2 _3 _4 _5 _6 _7 _8 _9 _10 10 9 8 7 6 5 4 3 2 1 0
/:~&.(22 b.&_16b8000) i:10
Sort and rotate?
(|.~ +/@:<&0)@(/:~) _10+10?.@$20
4 6 6 6 9 _5 _4 _4 _2 _2
Elijah Stone wrote:
> This is not terrible, though the >: rankles:
>
> (/: ] + 0&> * [: >: >./ - <./) i: 10
> 0 1 2 3 4 5 6 7 8 9 10 _10 _9 _8 _7 _6 _5 _4 _3 _2 _1
>
> I am sure somebody else has a
Man. Meeting The Hui was one of the top items I had on my bucket list...
It approaches midnight here as I sit and contemplate the vastness of Roger's
causal ripples, ever expanding into spacetime. Listening to the recapitulations
of his peers, indeed many of these ripples sound more like
"John Dell'Aquila" wrote:
> Hi all,
>
> I just discovered J a few months ago and have decided to take it up
> seriously. I wish I'd found it 20 years ago. You folks keep a seriously low
> profile on the internet :-)
Welcome John! The low profile here is definitely counterbalanced by the
BTW, it looks like GitHub is missing the j903-beta-r tag.
Eric Iverson wrote:
> J903-beta-r is available for windows/linux/macos.
>
> !!!
> The tacit-modifier language from early versions of J has been reinstated.
> Old J books are once again valid.
> !!!
>
> If you already run J903-beta, then
@Pascal
Thanks for going out on limb and starting this discussion. Personally, I find
the current modifier train parsing table relatively intuitive, but you
definitely got me wondering *why* I do. FWIW, the proposal you share seems to
mostly just save parentheses, which at first blush, feels to
Henry Rich wrote:
> And because they're cool.
So much yes! Extremely pumped about this!
--
For information about J forums see http://www.jsoftware.com/forums.htm
Late to the party, but what about simply thinking of (map) as indexing into the
cartesian product ({'abc';'ABCD')?
(({'abc';'ABCD') {~ $ <@#: I.@,) map
┌──┬──┬──┬──┐
│aA│aD│bB│bC│
└──┴──┴──┴──┘
--
For
On 2021年6月16日 18:07:54 JST, 'Rudolf Sykora' via Programming
wrote:
>Hello,
>
>
>>> what libraries are actually needed to get an output of 'plot' on
>>> screen?
>>> Is qt needed for that?
>
>Julian Fondren writes:
>
>> system/main/stdlib.ijs has a list of commands that it tries in
>>
While we're on this thread, I might as well share the couple pieces I have
laying around:
NB. Output a random depth vector of length y
rv=: <:@(1&= # +/\)@(|.~ >:@(i: <./)@(+/\))@(A.~ ?@!@x:@#)@($&1 , $&_1@<:)
NB. Pretty print a tree representation, given a depth vector (inspired by xash)
TM=: 3
Raoul Schorer wrote:
> Dear all,
>
> I am struggling with the translation of the following APL dyad to J:
>
> ∊ 0 {(⊢,(⍺+1)∇⊣)/⌽⍺,1↓⍵} y
>
> which is the expression to yield a depth vector from a tree in record
> format (drawn from Dr. Hsu's thesis). Demo:
Oh cool! I have been (very
9!:14''
j902-b/j64avx2/linux/release/GPL3/guix.gnu.org/1970-01-01T00:00:00/clang-9-0-1/SLEEF=1
+&1^:_1 i.3
_1 0 1
+&1^:_2 i.3
_2
$$ +&1^:_2 i.3
0
Similar results for other negative exponents smaller than _1.
My beta is a bit behind, but I see the
Is monadic # what you're looking for?
mask # chars
BEG
HH PackRat wrote:
> Hello, all!
>
> I have a list of characters and a boolean list of 1s and 0s. I
> thought that I could use the boolean list as a "mask" to choose
> characters by using "and" (*.). But the definition in NuVoc
On 2021年4月14日 16:18:07 JST, Emir U wrote:
>Hi Ian, Python is an example of a language with solid package
>management and repository (Pypi), FFI, parallelism support (e.g. Dask),
>and data structures. Julia is another. They also both have extensive
>eco-systems for data science oriented tasks.
Hello J,
"The Edges of Our Universe" is a nice and very accesible paper by Toby Ord that
discusses different natural "edges" to the universe that arise in General
Relativity (and in particular the ΛCDM model) and some futurist implications.
https://arxiv.org/abs/2104.01191
Anyway, the tail end
Henry Rich wrote:
> IF you want to get yourself in shape to make JE changes, I have a
> starter project for you: replace the extended-integer and rational
> support with GMP (or some other equally-good library). The current code
> is serviceable but sized for 32-bit machines, and lacks fast
Raul Miller wrote:
> https://github.com/jsoftware/jsource/commits/master might interest you...
Indeed, I have the repo cloned locally!
However, when digging through old bug reports, I find it quite challenging to
match up the "fixed" notices with the corresponding code commits. In cases with
a
Such a quick turnaround on bug reports, as always, Henry!
I'm invariably interested in the code fixes themselves. Would it be a hassle to
include some tidbit about how you solved the issue? Even just including the
`git log -p -` output (where the fix is spread over n commits) might be nice
for
me studying to understand, but that is exactly
> what I needed. Thanks so much!
>
> Skip
>
>
> Skip Cave
> Cave Consulting LLC
>
>
> On Sat, Oct 31, 2020 at 1:33 AM ethiejiesa via Programming <
> programm...@jsoftware.com> wrote:
>
> > What about so
What about something like this?
(|.~ ,.@i.@#)&.> n
┌─┬─┬───┬───┐
│1 2 3│4 5 6 7 8│8 6│3 5 7 9│
│2 3 1│5 6 7 8 4│6 8│5 7 9 3│
│3 1 2│6 7 8 4 5│ │7 9 3 5│
│ │7 8 4 5 6│ │9 3 5 7│
│ │8 4 5 6 7│ │ │
└─┴─┴───┴───┘
Right now, NuVoc documents that the rows returned by (1!:0) have 5 fields, but
I am seeing 6 in my version and platform:
1!:0 '.'
┌─┬──┬───┬───┬──┬──┐
│.│2019 9 14 10 51 16│264│rwx│-h--d-│drwxr-xr-x│
└─┴──┴───┴───┴──┴──┘
Oh! Duh. I was confused. (0!:0) directly executes the string (or file).
Much clearer now. Thank you.
Raul Miller wrote:
>example=: 3 :'echo 1'
>0!:0'example'
>0!:0'example 0'
> 1
>
> Put different: when you evaluate a bare name which references a verb,
> the result of that execution
Say we have a file ~home/script.jis with the following contents:
a=. 'bar'
and start a J session:
a=. 'foo'
verb=. 0 :0
a=. 'baz'
)
a
foo
0!:0 http://www.jsoftware.com/forums.htm
Bo Jacoby wrote:
> How to de-smell this:
> 3([* i.@#@,@[ ^/ i.@>:@])~ 0 0 1 1 1
3 (]* ((^/ >:)~ #)) 0 0 1 1 1
Maybe? That comes from just a little mechanical algebra:
> 3([* i.@#@,@[ ^/ i.@>:@])~ 0 0 1 1 1
First notice the repeated (i.) on either argument of (^/). There is a general
Bo Jacoby wrote:
> How to remove the smell (the "[" and the "]") from
> 3(i.@>:@[ ^/~ ])2 3 4
> ?
3 (^/ i.@>:)~ 2 3 4
In general, when you want to "preprocess" only one argument of a dyad, a hook
probably does what you want.
Cheers
What are some classes of code smell in J?
For clarity, "code smell" means any characteristic of source code that
indicates a potentially deeper problem. These are anti-patterns that occur at
the source code level.
The canonical example is probably duplicated code, which indicates a potential
for
x...@xn--wxa.land wrote:
> For your original format, with a transition matrix to simplify finding
> "catenaries" for each column:
>
> tm=:3 4 $ 0 1 0 1 2 2 2 2 3 1 3 1
> start=: 0,~ = + 2*(=>:) NB. same height = 1, direct children = 2, others
> = 0
> step=: {::@, NB. apply
> Alternative (slightly more compact) implementation of tv:
>
>tv=: (0 = {.) *./@, (0 < {:), 1 >: +/\inv
Nice way to factor out the (*./) redundancy. Thanks.
> Meanwhile, this is probably a bit long (almost 100 characters) to be
> called a one line implementation, but it seems to be in the
Thanks for the thoughts!
> not as pretty, but simpler and pretty enough?
>
> (":"0@i.@# (,~ #&'-')"1 0 ]) 0 1 2 2 1 1 2 2 3
>
> 0
>
> -1
>
> --2
>
> --3
>
> -4
>
> -5
>
> --6
>
> --7
>
> ---8
This is sort of in between the raw depth vector and the graph representation.
It's probably
Do you know a slick way of pretty-printing a tree given its depth vector
representation?
A vector represents a tree if and only if it satisfies the following:
NB. Tree valid? First node is root node (depth 0), only one root node,
NB. and all nodes are exactly one deeper than their
Oops.
> Let <. : R+ -> Z+ where (<.r) is defined to be the extended integer such
> that there exists a real number s in the interval [0,1) and ((<.r)=|s-r).
((<.r)=|s-r) should be ((<.r)=r-s).
--
For information about J
> So J is saying that the floor of infinity is infinity (and the ceiling of
> infinity is also infinity). Since infinity is not a number, it would seem
> that an error should be generated when taking the floor of infinity, or
> perhaps NAN, or a zero? In any case, this messes up my nice
John,
> You can encapsulate mode, median and mean in a single formula. Suppose y is
> a data vector and t is a scalar. The a value of t which minimizes
> +/ (|y-t)^i [with special meaning for x^0: see below] is
> - A mode of y if i=0.
> -A median of y if i=1.
> -The mean of y if i=2.
Neat!
Bayes' Theorem.
For let k=:?p, then for every integer i in i.p
P(k=i) = 1/p.
We can then model your selective keeping process with a posterior distribution
on this pdf. For every i in i.q,
P(k=i|k wrote:
> A question for the statisticians and mathematicians among us.
>
> Suppose I
ssary.
> > >
> > > This leaves some details unspecified -- like should you use ". or 5!:5
> > > or 3!:1 or map_jmf_ in the process of generating the 'o' files?
> > >
> > > But, anyways, if you defined the interface you could use it.
> > >
>
Responding to you with a good bit of lag:
> > My first approach was to "lazy load" by making all p1, p2, etc. strings
> > and
> > evaluating with
> >
> > 0!:111 ".&> (#~ 0 = 4!:0) 'p'&,&.> ARGV
> >
> > However, this strikes me as a bit ugly. It also makes it a bit awkward
> > to
> >
Hey J,
Wanted to share this and see what you think.
For Project Euler solutions in J, I have a single file and run it like this:
$ ./project-euler.ijs <1> [ ..] # output answers to problem n, m, ...
Initially, I had a scheme where all solutions are named like p1, p2, etc. with
the
Excellent! Can we push a release tag on the GitHub repo? Looks like it's
missing at the moment:
https://github.com/jsoftware/jsource/releases
Eric Iverson wrote:
> j901-release-f fixes the serious bug reported by James Kozianski a few days
> ago.
>
> All j901 users should upgrade!
>
> start
ds, Anton Wallgren
> On 26 May 2020, 10:39 +0200, ethiejiesa via Programming
> , wrote:
> > Hey Anton,
> >
> > Welcome to the J-verse!
> >
> > FWIW, the question as stated makes me suspect that you're (unconsciously)
> > trying to fit J into an imperative pro
Hey Anton,
Welcome to the J-verse!
FWIW, the question as stated makes me suspect that you're (unconsciously)
trying to fit J into an imperative programming paradigm. I would venture that
you'd get better answers by more directly sharing what you're trying to
accomplish and the problems thus
Not Skip, but let me take a crack at an explanation.
I agree that NuVoc's wording makes it sound like monadic { doesn't work on
unboxed lists. However...
{1 2 3
┌─┐
│1 2 3│
└─┘
{<1 2 3
┌─┬─┬─┐
│1│2│3│
└─┴─┴─┘
So { certainly does *something* to
Brian Schott wrote:
> All,
> I think Bill's solution works for my question: dbover'' (13!:20).
> In contrast to Gilles, I think dbinto'' (13!:21) works as designed, because
> changing the value of t to 99 does not change the code in line [0], which
> it then executes with dbinto or dbover.
>
>
Rudolf Sykora wrote:
> Dear all,
>
>
> how do you usually generate a sequence of integers from 'a' to 'b' with
> a step 's'?
>
> If I ignore the step, yesterday I wrote
>
>interval=.{.+(i. @ >: @ ({:-{.))
>interval 5 19
> 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
>
> but that seems
Raul Miller wrote:
> Another possible way to emphasize what's going on here might be to
> split 'v' up into multiple instances (one for each cell) in the &
> case. (Though, there, drawing a box around the 'v' part, to show the
> scope of the verb and distinguish the definition from the
This was me. Very nice to hear that someone found it helpful. Thanks for going
out of your way to say thanks!
Jim Russell wrote:
> Who do I thank tor this? It is a particularly clear and helpful exclamation.
> Thank you!
>
> > On Mar 13, 2020, at 3:56 AM, ethiejiesa
|: }
> but being aware of what it does for you will make
> you find it’s useful in many more cases.
>
> hope this helps
>
>
> Am 13.03.20 um 08:55 schrieb ethiejiesa via Programming:
> > I'll contribute a little prose. Hopefully, it's helpful.
> >
> > I
I'll contribute a little prose. Hopefully, it's helpful.
In this particular case, notice that > transforms your list of boxes into a 5x6
table:
> (6?55);(6?55);(6?55);(6?55);(6?55)
13 4 19 43 3 52
10 1 4 46 52 11
38 12 48 50 54 45
36 54 39 35 53 50
44 1 7 54 11 41
NuVoc notes what replaces D. and d. on their respective pages.
In particular, from the math/calculus addon, we have
* deriv_jcalculus_ to replace d. and
* pderiv_jcalculus_ to replace D.
Skip Cave wrote:
> In "Fifty Shades of J" chapter 23, the Newton Raphson algorithm is
> described thusly:
>
Fair enough. Thank you for the clarity.
Henry Rich wrote:
> My build setup depends on considerations that transcend this
> discussion. Take it as given.
>
> Henry Rich
>
> On 1/30/2020 10:43 PM, ethiejiesa via Programming wrote:
> > Hrm. That's quite odd.
> >
&g
-agnostic build systems.
What build setup are you using?
Henry Rich wrote:
> The funny includes are required on the build system I use. If you put
> your source under a /jsource directory you will be able to use the files
> as is.
>
> Henry Rich
>
> On 1/29/2020 11:
Compilation on linux breaks for me:
../../../../jsrc/cip.c:6:10: fatal error: ../../jsource/jsrc/j.h: No such
file or directory
6 | #include "../../jsource/jsrc/j.h"
| ^~~~
It looks like `jsrc/cip.c' includes paths that back all the way out of
This is a beautiful list! Thank you for sharing.
Regarding your 3) and 6) versions with modulo arithmetic, happily, this is a
standard result from number theory. You should be able to find the relevant
background and theorem itself near the beginning of any introductory Number
Theory book. IIRC,
Beautiful. Just FYI, but it looks like the github mirror still isn't picking up
git tags from the parent, so the github source releases are out of date.
Eric Iverson wrote:
> j901-release-c is available for windows/linux/macos
>
> It has bug fixes to the previous release.
>
> Please upgrade
FWIW, my non-avx system doesn't reproduce the crash:
#. 0$0
0
9!:14''
j901/j64/linux/release/GPL3/voidlinux.org/2019-12-15T23:11:06
Ben Gorte wrote:
> Hi J,
>
> Base 2 on an empty array gives 0 , which I guess makes sense:
> #. '' NB. array with no characters
> 0
Oh wow. Just stumbled across this myself.
FWIW, doing the dumb thing by copying the url and changing 807 to 901 does
work.
Arnab Chakraborty wrote:
> I must be missing something obvious, but I do not seem to be able to find
> jandroid.apk for j901. All I get is j807. Please help.
>
> Thanks a
ould see the tag "j901-release-a1" for
> the commit which was used for the current 901 builds.
>
> On Sun, Dec 15, 2019 at 7:19 PM ethiejiesa via Programming <
> programm...@jsoftware.com> wrote:
>
> > Excellent news! And congratulations to all the developers.
> >
com/wiki/Essays/Queens_and_Knights
> Harder version of the n-queens problem.
> See also the pages in the "See also" section.
>
> etc.
>
> On Thu, Dec 12, 2019 at 6:37 PM ethiejiesa via Programming <
> programm...@jsoftware.com> wrote:
>
> > Hello
Excellent news! And congratulations to all the developers.
Can we expect the github repository to reflect the update soon? It seems to be
quite out of date. I am the J package maintainer for Void Linux, and this
distro doesn't accept pre-built packages in general.
Eric Iverson wrote:
> We are
Hello J,
Using J primitives, what are some nice algebraic identities you know of?
I recently acquired a copy of "At Play with J" and in the process of mulling
over chapter 7's permutation representations, I stumbled upon this nice one,
which I assume is already well known:
/: -: /:@/:@/:
──┴───┴────┘
>
>
>
> On Fri, Dec 6, 2019 at 9:54 PM ethiejiesa via Programming <
> programm...@jsoftware.com> wrote:
>
> > Am I just doing something silly? Or does @. really not support building
> > trains
> > when the right operand is a verb? H
Am I just doing something silly? Or does @. really not support building trains
when the right operand is a verb? Here is an overly minimal example of what I
want:
(1:)`+`(1:)@.(0 1 2) 0
2
(1:)`+`(1:)@.(0 1 2"_) 0
|rank error
| (1:)`+`(1:)@.(0 1 2"_)0
This is an
It's basically a consequence of the parsing rules:
https://www.jsoftware.com/help/dictionary/dicte.htm
In this case, when given 'abc' by itself, your J session tries to return the
value, finds none, so produces an error. However 'xyz abc' parses as a hook, so
the "value" returned is its linear
Playing around with type bounds, I just discovered these things about ^ that I
don't recall seeing in the documentation:
9!:14 ''
j807/j64nonavx/linux/release/GPL3/voidlinux.org/2019-09-30T12:27:01
2&^ 1023 1024
8.98847e307 _
(3!:0)@^&>/~ 0;1;2
4 4 8
4 4 8
I assume this is well known by the cognoscenti, but I just ran into a newbie
surprise:
<. _1e_14j0
_1
<. _1e_14 j. 0
0
This came about as I was learning about and playing with the complex floor.
Apparently, the differing behaviour traces back to how tolerance is handled
Thank you for the thoughtful and lucid reply.
If you don't mind, let me check my understanding.
So, essentially, we keep forefront the general concept of numeric words
requiring speculative tokenization in the sense you describe.
Is the following true? Let sj be the state table as defined in
for a subsequent ev() to be emitted at all, much less one when r = 6.
Forgive me if I'm just being obtuse here.
On Sun, Oct 06, 2019 at 08:46:53AM -0400, Raul Miller wrote:
> On Sat, Oct 5, 2019 at 9:21 PM ethiejiesa via Programming
> wrote:
> > > What would it emit instead?
>
I seem to be having troubles with the mailing list. Please forgive the
overlapping replies with similar content.
--
For information about J forums see http://www.jsoftware.com/forums.htm
you
> then have to change the parser (
> http://www.jsoftware.com/help/dictionary/dicte.htm) to handle two or more
> numbers juxtaposed.
>
>
>
> On Thu, Oct 3, 2019 at 11:57 PM ethiejiesa via Programming <
> programm...@jsoftware.com> wrote:
>
> > Just begin
r Hui wrote:
> > emits no vectors
>
> What would it emit instead? If you emit individual scalar numbers, you
> then have to change the parser (
> http://www.jsoftware.com/help/dictionary/dicte.htm) to handle two or more
> numbers juxtaposed.
>
>
>
> On Th
in the behaviour?
>
> Cheers, bob
>
> > On Oct 5, 2019, at 6:21 PM, ethiejiesa via Programming
> > wrote:
> >
> >> What would it emit instead?
> > Words that just happen to contain spaces.
> >
> > I just realized, however, that my origin
> What would it emit instead?
Words that just happen to contain spaces.
I just realized, however, that my original email example lets number words
contain trailing spaces. So, I agree that the cell "0 5" in the state table
needs to be what it is. However, if we're in state num and encounter a
Just beginning to learn J this week, I find myself binging the documentation
and have some questions regarding J lexing. In particular, my question is about
the sample J lexer presented in the dyadic ;: entry of the dictionary:
https://www.jsoftware.com/help/dictionary/d332.htm
Essentially,
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