I like that solution. Here is another approach
4 p.~(2&^@>: ,.~ _1r3 * 2&^@>: + _1&^)i. 10
7 15 29 59 117 235 469 939 1877 3755
I found this by composing the linear poly's and noting the constant
terms satisfy a two step recursion with eigenvalues 2 and _1.
lc=.({.@[+{:@[*{.@]),*&{:
Hi,
The Journal of J (http://www.journalofj.com/) published an issue in June
of this year. I indulged the fact that it is an electronic journal to
write an article with 108 figures (47 pages). It was on finding cellular
automata that exhibit complex behavior using some statistics. The most
From Mathematica help:
Map (Built-in Symbol)
Map[f, expr] or f /@ expr applies f to each element on the first level
in expr. Map[f, expr, levelspec] applies f to parts of expr specified by
levelspec. Map[f] represents\[Ellipsis]
On 9/5/2018 10:58 AM, devonmcc wrote:
I am trying to bring
Your 13 created a tacit verb
taher=: 13 : '%: s2 * */ s2-y [ s2=. -: +/ y'
taher
[: %: ([: -: +/) * [: */ ([: -: +/) - ]
On 9/4/2018 7:50 AM, Martin Kreuzer wrote:
Hi all -
To calculate the area of a flat triangle, using Heron's formula,
A(a,b,c)= sqrt( s2*(s2-a)*(s2-b)*(s2-c) )
I
My first reaction to Bo's remarks (far below) was "well said and very
sensible" although my instinct was to use 1e8 near half the precision of
floats. I started playing with tacit versions and got to observe what I
thought was a surprising number of false positives.
First some tacit fun:
That sounds like a good, useful plan.
On 5/12/2018 8:55 AM, chris burke wrote:
~config/winpos.dat is used by Jqt to remember the positions of some
windows. It could be used for wd forms as well.
We need to agree on how it should work.
Right now we have wd 'pmove x y w h' to set the position.
I am guessing there is a bug in b formatting. Note, even base 10:
10b123456789010234567
123456789010234560
10b123456789010234562
123456789010234560
Almost seems like it went "float" internally or some such.
On 4/25/2018 11:12 AM, Thomas Hickey wrote:
Maybe a better question is why are
Not sure this helps:
]n=:(8#256) #: 81985529216486896x
1 35 69 103 137 171 205 240
Note the 240 in n
_3 ic |.n{a.
81985529216486896
On 4/25/2018 10:29 AM, Thomas Hickey wrote:
I have a 64 bit number:
16b123456789abcdef = 81985529216486896
encoded in 8 bytes in a file:
239 205 171 137
Hi,
Just a remark that I finally submitted the paper I had in mind to the
Journal of J. It might be a good time to let the editor know if you have
plans to submit a paper reasonably soon.
Happy J'ing
Best, Cliff
On 4/19/2017 1:06 AM, mikel paternain wrote:
Send papers to
]a=:10 6 8 <@?@$"0] 2
+-+-+-+-+-+-+-+-+-+-+
|1|1|1|1|0|0|0|1|0|1|
+-+-+-+-+-+-+-+-+-+-+
|0|1|1|1|0|1| | | | |
+-+-+-+-+-+-+-+-+-+-+
|0|1|0|1|1|0|0|1| | |
+-+-+-+-+-+-+-+-+-+-+
<@;"1 a
+---+---+---+
|1 1 1 1 0 0 0 1 0 1|0 1 1 1 0 1|0 1 0 1 1 0 0 1|
Pascal,
I assume you meant that you got no feedback from the editor? Pity if so.
Have you thought about asking the forum for feedback? That would
probably have a good overlap in readership.
Best, Cliff
--
For information
Dear J forum,
Writing for the Journal of J or Vector is different from writing for the
Jforums or Wiki. All those venues are a valuable resource for us who
work with J. I encourage us to supply all those forums with material. I
submitted a paper to Vector a few months ago:
A cut variant of "words"
(<;.1~1,2 ~:/\ ])I
+-++---+---+-++
|a||aaa|ccc|a||
+-++---+---+-++
On 2/18/2018 1:22 PM, David Lambert wrote:
While not answering your question, the verbs f f g and h solve the
problem. The first f uses complex copy to
Poking around
coclass 'jviewmat'
names''
Maybe changing DEFWH would be more appropriate. (untested)
On 12/31/2017 1:32 PM, Cliff Reiter wrote:
This may not be a good choice as I don't understand all the
consequences and hesitate to change values in addons authored by
others, but you might
This may not be a good choice as I don't understand all the consequences
and hesitate to change values in addons authored by others, but you
might try:
MINWH_jviewmat_=:1000 1000
or a variant suited to your device and data.
On 12/31/2017 12:17 PM, Dabrowski, Andrew John wrote:
I'm looking
From https://en.wikipedia.org/wiki/Short-circuit_evaluation is the
following paragraph [some special symbols don't jive with a remark, but
the other remarks are the point I want to highlight]:
The use of short-circuit operators has been criticized as problematic:
The conditional
Two possible leads (without chasing the old threads):
(1) fvj4/dwin.ijs or chapter 10 in FVJ4
load '~addons/graphics/fvj4/dwin.ijs' There is a FVJ4 dwin lab and some
examples in remarks at the end of the script. Not 3D point sets, but
they might be added small polygons used instead. Some simple
Does the following help parse the rank applications
a ;"0 1"1"1 2 b
+-+-+
|2|1 1 1|
+-+-+
|3|1 1 1|
+-+-+
+-+-+
|2|1 2 1|
+-+-+
|3|1 2 1|
+-+-+
+-+-+
|2|1 1 1|
+-+-+
|3|1 1 1|
+-+-+
+-+-+
|5|1 1 1|
+-+-+
|7|1 1 1|
+-+-+
+-+-+
|5|1 2 1|
I think kr=: [: ,./^:2 */ is what (or close to it) we came up with then.
My retest 18 years later wasn't so good :).
kr=:[:,./ [: ,/"_1 */
I like the expressiveness of Roger's *"0 2
Thanks for the interesting ideas and solutions. Cheers, Cliff
On 10/14/2017 12:36 PM, Roger Hui wrote:
The idea is to write a verb which gives the Kronecker product.
https://en.wikipedia.org/wiki/Kronecker_product
For example:
]a=:2 2$2 3 5 7
2 3
5 7
]b=:1+4=i.3 3
1 1 1
1 2 1
1 1 1
a kr b
2 2 2 3 3 3
2 4 2 3 6 3
2 2 2 3 3 3
5 5 5 7 7 7
5 10 5 7 14 7
5 5 5 7 7 7
Note each entry
2 { 1 2 3
3
This was a revelation:
{2#<'123'
┌──┬──┬──┐
│11│12│13│
├──┼──┼──┤
│21│22│23│
├──┼──┼──┤
│31│32│33│
└──┴──┴──┘
Skip
Skip Cave
Cave Consulting LLC
On Tue, Oct 3, 2017 at 10:21 PM, Cliff Reiter <reit...@lafayette.edu> wrote:
A cheat (?) that builds instea
A cheat (?) that builds instead of "removing"
z=.,".>{4#<'123456'
$z
1296
10{.z
1112 1113 1114 1115 1116 1121 1122 1123 1124
On 10/3/2017 4:16 PM, Skip Cave wrote:
Another interesting Quora problem:
Given the integers from 1000 to , remove all integers that contain a 7,
8,
j64-8.05
If you have downloaded all the addons, try:
load '~addons/debug/dissect/dissect.ijs'
On 3/12/2017 1:27 PM, Linda A Alvord wrote:
Bill, I have avoided trying the beta until I know what I can and cannot do in
805 and j64-805
Load 'dissect' is still not ok in 805
Linda
Linda, I think something you wrote or sent me a couple years ago
inspired me to write a Vector note on Fibonacci spirals:
http://archive.vector.org.uk/art10501110
A bit involved for grade 4 or 5 though.
Best, Cliff
On 2/28/2017 10:01 AM, Linda A Alvord wrote:
Cliff, I'm never quite sure where
' ',"1 ":,.>:i.y),"1 '),''
|domain error: fib2
| {.W^:y 0 1
It doesn't like the fact that that the fib2 should still be just letters.
It was fun anyway. Linda
-Original Message-
From: Programming [mailto:programming-boun...@forums.jsoftware.com]
Here are a couple approaches:
First, make a list, then take the last thing in it.
fib_list=:3 : 0
z=.0 1
for. i.y-1 do.
z=.z,+/_2{. z
end.
if. y>0 do. z else. 0 end. NB. this only used to make fib_list 0 correct
)
fib_list 10
0 1 1 2 3 5 8 13 21 34 55
fib=:{:@fib_list
fib 10
55
Hi,
The second part of my text, Fractals, Visualization and J, 4^th edition,
Part 2, is now available from lulu.com. It was tested under JQT 8.04
and/or 8.05. It is available both in print and as a PDF. Note: updates
to ~addons/graphics/fvj4 and ~addons/media/imagekit used by this book
were
A long, long, time ago in a J far away, indexing was done in i. order.
So indices to a 3 by 2 array would be given by
i.3 2
0 1
2 3
4 5
Is it possible that x u}y is an artifact from that era?
On 12/27/2016 3:06 PM, Don Guinn wrote:
Just played with the original expression a little
Feel free. My attention is on Part 2.
On 3/1/2016 1:22 PM, Raul Miller wrote:
Someone created a couple rosettacode pages:
http://rosettacode.org/wiki/Barnsley_fern
and
https://en.wikipedia.org/wiki/Chaos_game
which correspond roughly to sections 4.4 and 4.5 of your book.
Do you feel like
regularly does 25%-off
offers, which covers the shipping).
[Disclaimer: reviewer has bought his own copy.]
On Fri, Feb 26, 2016 at 12:07 PM, Cliff Reiter <reit...@lafayette.edu> wrote:
I posted this in Jchat, but was encouraged to also post here. Apologies for
the overlap.
Hello fell
I posted this in Jchat, but was encouraged to also post here. Apologies
for the overlap.
Hello fellow Jer's,
I have released print and PDF versions of
Fractals, Visualization and J, Fourth edition, Part 1
at lulu.com. Compared to the 3rd edition, there are several new
sections, fairly
, Cliff Reiter <reit...@lafayette.edu> wrote:
I think the first time I saw gerund insert, Ken Iverson showed off
+`%/10# 1x
13r8
getting Fibonacci approximations to the Golden ratio, so I always expected
it to be "from the front".
Seeing this thread, I decided to exper
I think the first time I saw gerund insert, Ken Iverson showed off
+`%/10# 1x
13r8
getting Fibonacci approximations to the Golden ratio, so I always
expected it to be "from the front".
Seeing this thread, I decided to experiment but forgot to "insert" and
got something unexpected:
Devon,
I have done much the same thing in preparation for Fractals,
Visualization and J, 4th ed., Part 1, which I hope is soon.
My addons media/image_kit and graphics/fvj4 really could also be
posted. I control the default jpeg quality with a global (now 90) as in
the old image3.
Advice on
Nice work. I believe the smoothing that you see is due to the max bound
on the number of iterations (24). But as you raise that, things slow down.
On 1/2/2016 9:11 PM, Michal Wallace wrote:
Hey all. Happy new year!
I made a small GUI app for a tutorial video I'm planning:
In J6.02 there was a script
'~system/extras/util/browser.ijs'
that defined
launch_jbrowser_
Is there anything analogous in J8.03 (or 8.04)
--
For information about J forums see http://www.jsoftware.com/forums.htm
.
)
nx_WIN=:3 : 0
try. WIN_num=: WIN_num + 1 catch. WIN_num=: 0 end.
WIN_nam=:'p',: WIN_num
)
delay=:6!:3
WIN_WH=:500 500
sq=:#: 0 1 3 2
_2 _2 2 2 0.1 dawin 'rot'
rot=:(cos,sin),:-@sin,cos
R=:(rot 1r40p1)(+/ . *)1
$pl=:R^:(i.120) sq
0 255 0 dapoly pl
On 4/26/2015 6:47 PM, Cliff Reiter
The wd 'msgs' solved both problems in both contexts.
Thanks, Cliff
On 4/26/2015 7:03 PM, bill lam wrote:
you are running a tight loop. add
wd'msgs'
before the line
delay DELAY
On Apr 27, 2015 6:52 AM, Cliff Reiter reit...@lafayette.edu wrote:
You need some access to gl2.ijs too
nx_WIN=:3 : 0
try. WIN_num=: WIN_num + 1 catch. WIN_num=: 0 end.
WIN_nam=:'p',: WIN_num
)
On 4/26/2015 5:54 PM, Raul Miller wrote:
I get a value error on nx_WIN
Thanks,
--
For information about J forums see
An object animation example follows some remarks.
I may have found the answer to my question.
That short script has the correct behavior so long as the last line is
run in the script and not loaded. If loaded, the same problem occurs. In
the rast case I am trying to open and update the window
Infinity is a float.
3!:0]_
8
Extended precision arithmetic does not promote to float, so rather than
reaching infinity, it reaches a limit error. At least that is how think
about it.
Best, Cliff
On 2/17/2015 2:23 PM, Fausto Saporito wrote:
Hello,
yes the number is very big, but why
Yes, thank you.
On 2/8/2015 4:11 PM, Henry Rich wrote:
Maybe you want an isidraw control rather than an isigraph.
Henry Rich
On 2/8/2015 3:59 PM, Cliff Reiter wrote:
I have working with gl2 and the graphics package to try to understand
how to update a isigraph window in J8.03 (windows
I have working with gl2 and the graphics package to try to understand
how to update a isigraph window in J8.03 (windows). The gl2 demos seems
to put all the data in the paint event and it would be nice if the data
could be created after the window. In the graph package lab, examples
where this
Lovely. Tiny remark:
-.@+. could be replaced by +:
On 1/26/2015 1:00 AM, Raul Miller wrote:
A note of explanation...
(I have been noticing that far too much software is poorly documented.
And while I cannot do an adequate job of documenting other people's
software, I can document software I
Lovely
On 10/22/2014 10:44 PM, Marshall Lochbaum wrote:
Everything is reduce!
([*+)/\..|. 1 0 1 1 1 1 0 1
1 0 1 2 3 4 0 1
Marshall
On Wed, Oct 22, 2014 at 01:10:34PM -0400, Joe Bogner wrote:
This is probably easy but I can't figure it out. How can I count the number
of consecutive 1s?
And there is key
(]/.~2|i.@#)i.8
0 2 4 6
1 3 5 7
which handles the odd case with an easy variant
(/.~2|i.@#)i.9
┌─┬───┐
│0 2 4 6 8│1 3 5 7│
└─┴───┘
On 10/9/2014 7:20 PM, Raul Miller wrote:
I'd probably go with
i. 8
0 1 2 3 4 5 6 7
|:_2]\ i.8
0 2 4 6
1 3 5 7
But
Nice. In FVJ3 I use
spix=:[ # #_1 NB. super pixel
The _1 means this also works for h by w by 3 arrays of RGB triples in
addition to matrices.
Best, Cliff
On 7/16/2014 6:32 PM, 'Pascal Jasmin' via Programming wrote:
spoiling quiz with answer already, neat short fork.
zoom =: [ # #1
for
I wrote a note
Prime Factorization in the Gaussian Integers, /Journal of J/, 2 1 (2013) 4-
that might be of interest. The scripts from that note are
https://webbox.lafayette.edu/~reiterc/j/JoJ/gi_factor_notes.html
https://webbox.lafayette.edu/~reiterc/j/JoJ/gi_factor.html
Best, Cliff
On
In light of the link provided by R.E.Boss and x: on complex numbers
x: 1j1
|domain error
| x:1j1
|[-0]
We might define rational query as occurring when the denominator of the
rationalization is small and not an error
ratq=:(1e8{:@:(2x:)) :: 0:0
ratq ?10$0
0 0 0 0 0 0 0 0 0 0
?
y=:13
((ruq i:y)-:((1=i:y)+.(_1=i:y)))
1
y=:14
((ruq i:y)-:((1=i:y)+.(_1=i:y)))
1
Linda
-Original Message-
From: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Cliff Reiter
Sent: Monday, June 02, 2014 9:17 PM
Pascal,
For my implementation, look at p129 in the first link for conversion
from (x,y) to (x,y,z).
Note, the (corrected) script from my notes are available
http://webbox.lafayette.edu/~reiterc/j/vector/factor_ecj.html
but using x. y. era notation and lots of x y local variable so updating
to
Some elliptic curve stuff; I think there is a +1 error that Roger Hui
noticed in the factorization method.
http://archive.vector.org.uk/art10007270
http://archive.vector.org.uk/art10007280
Best, Cliff
On 1/29/2014 11:35 AM, Pascal Jasmin wrote:
With all of the mathematicians on this list,
For modular inverses in teaching I use
gcd2x=: 3 : 0
'r0 r1'=.y
's0 s1'=.1 0
't0 t1'=.0 1
while. r1 ~: 0 do.
q=. . r0 % r1
'r0 r1'=. r1,r0-q*r1
's0 s1'=. s1,s0-q*s1
't0 t1'=. t1,t0-q*t1
end.
r0,s0,t0
)
invmod=: 4 : 'y| {: gcd2x y,x'
5 invmod 21
17
21|5*17
1
Best, Cliff
On
David,
You probably want 256 256 256 256#: and then to figure out which of the
4 coordinates you want.
Are you using windows? I have a image io script that does basic
read_image and write_image
analogous to image3 for 64bit windows. Not as complete as image3 and I
view some things as
Is there a reason to prefer (*|@*) over (**|)?
ts=:6!:2 , 7!:2@]
1000 ts'(* |@*).+. ^ 0j1 * 1r2p1 * i. 500'
0.00106239 43200
1000 ts'(**|).+. ^ 0j1 * 1r2p1 * i. 500'
0.000791911 43072
Best, Cliff
On 5/27/2013 1:34 AM, km wrote:
I didn't think of Signum! Thanks, Roger.
Sent from my
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