Oops, I did not think about that "reflexive giving" wart.
Here's a fix for my version:
tick=: (0 >. <:) + i.@# +/@:(=/)~ I.@:* (] + <:) +/@:* ?@# <:@#
require 'stats'
stddev"1 tick^:(i.10) 45#45
0 0.977008 1.18705 1.73205 2.01133 2.15322 2.46798 2.86832 2.97719 3.1334
tick^:10000]20#20
3 20 1 15 10 38 6 8 23 24 11 90 33 67 5 13 7 20 1 5
Thanks,
--
Raul
On Mon, Jul 10, 2017 at 7:50 PM, 'Pascal Jasmin' via Programming
<programm...@jsoftware.com> wrote:
>
>
> The number of $ available each round is the number of people with >&0. The
> number of potential recipients is the population. This simplification though
> means its possible for someone to pay himself.
>
>
> A correction to your version,
>
> /:~@(-&1`]@.(=&0)"0 (#/.~@] + ~.@]{[)`(~.@])`[} >&0 # (?@#~@#@]`]`[} ] I.@:=
> i.@#)@?@#~@#)^:21000 #~10
>
> That assumption would increase the likelihood of eventual "superconcntration"
> but that doesn't seem to happen.
>
> As soon as some have 0, the rest have a "negative return" expectation each
> turn.
>
>
> ________________________________
>
>
> From: Xiao-Yong Jin <jinxiaoy...@gmail.com>
>
> To: "programm...@jsoftware.com" <programm...@jsoftware.com>
>
> Sent: Monday, July 10, 2017 3:43 PM
>
> Subject: [Jprogramming] Everyone giving dollars to random others
>
>
>
>
> I thought this is a good lunch break exercise.
>
>
>
> http://www.decisionsciencenews.com/2017/06/19/counterintuitive-problem-everyone-room-keeps-giving-dollars-random-others-youll-never-guess-happens-next/
>
>
>
> Quote: “Imagine a room full of 100 people with 100 dollars each. With every
> tick of the clock, every person with money gives a dollar to one randomly
> chosen other person. After some time progresses, how will the money be
> distributed?”
>
>
>
> And I came up with this simulation. (45 people with 45 dollars each, same as
> on the webpage.)
>
>
>
> /:~@(-&1`]@.(=&0)"0 (#/.~@] + ~.@]{[)`(~.@])`[} >&0 # (?@#~@#@]`]`[} ] I.@:=
> i.@#)^:_@?@#~@#)^:5000 #~45
>
>
>
> And I really like to see the mean expectations and the standard deviation of
> the mean, I ended up doing this. (Make sure the J sentence is one long line
> if you want to try it out.)
>
>
>
> ((],.[:(+/%#*<:@#)&.:*: -"1)+/%#)}.(/:~@(-&1`]@.(=&0)"0 (#/.~@] +
> ~.@]{[)`(~.@])`[} >&0 # (?@#~@#@]`]`[} ]I.@:=i.@#)^:_@?@#~@#)^:10000)^:(<65)
> #~45
>
>
> 0.984375 0.124984
>
>
> 2.01562 0.170335
>
>
> 3.0625 0.180765
>
>
> 4.15625 0.230616
>
>
> 5.21875 0.248476
>
>
> 6.1875 0.306894
>
>
> 7.35938 0.332862
>
>
> 8.64062 0.362809
>
>
> 9.84375 0.380723
>
>
> 10.9688 0.383805
>
>
> 12.125 0.407944
>
>
> 13.6406 0.423964
>
>
> 15.0625 0.457453
>
>
> 16.5312 0.462893
>
>
> 18.1875 0.480717
>
>
> 19.7031 0.464877
>
>
> 21.1562 0.475709
>
>
> 22.7031 0.483702
>
>
> 24.4062 0.516935
>
>
> 26.4062 0.5768
>
>
> 28.1094 0.604266
>
>
> 29.8281 0.617838
>
>
> 31.875 0.61942
>
>
> 33.9375 0.603345
>
>
> 35.7812 0.642211
>
>
> 37.9844 0.647987
>
>
> 40.6562 0.731321
>
>
> 43 0.739342
>
>
> 45.3906 0.723616
>
>
> 48.0469 0.7613
>
>
> 51.6094 0.823639
>
>
> 54.7656 0.873934
>
>
> 57.1406 0.815544
>
>
> 60 0.866598
>
>
> 63.8594 0.898319
>
>
> 68.75 0.918018
>
>
> 73.5781 1.00736
>
>
> 78.3281 1.08128
>
>
> 84.9688 1.25534
>
>
> 93.4688 1.29731
>
>
> 104.578 1.73274
>
>
> 114.922 2.07574
>
>
> 131.938 2.7357
>
>
> 159.359 4.40899
>
>
> 204.766 7.24239
>
>
>
> So, how do I make a fancy animation (like the one in the webpage I linked in
> the beginning of this message) with J?
>
>
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>
>
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