Some probabilities fun


#1

Hello all.

Only wanted to show two short probability tricks, which can make use in
games or other “random” environments.


#Trick 1: use ~ sign to say “approximately”

class Numeric
LEVEL = 0.3
def ~
self + self * rand(LEVEL) - self* LEVEL/2.0
end
end

#testing it:

10.times{puts “=” * ~15.0}

#now you shall see 10 bars with random lengthes in range 15 ±15%
#can be used, for example, in game charactes move: go(~10.0),
turn(~15.0)

#!warning: we still leave Fixnum#~ as byte negation
#you can rewrite it too, but on your own risk!


#Trick 2: indeterminate event

def probable(pct)
yield if rand(0.99999999) < pct
end

res = 0

100.times{
probable(0.4){res += 1}
}
#100 times increase res with 40% probability

p res
#you should see something between 30 and 50…

Isn’t cool? :slight_smile:

V.