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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