random number with seed

Question

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i cannot understand the following line , can anybody provide me some example for the below statement?

If two instances of Random are cre

Answer 1

With the same seed value, separate instances of Random will return/generate the same sequence of random numbers; more on this here: http://www.particle.kth.se/~lindsey/JavaCourse/Book/Part1/Tech/Chapter04/javaRandNums.html

Ruby Example:

class LCG; def initialize(seed=Time.now.to_i, a=2416, b=374441, m=1771075); @x, @a, @b, @m = seed % m, a, b, m; end; def next(); @x = (@a * @x + @b) % @m; end; end

irb(main):004:0> time = Time.now.to_i
=> 1282908389

irb(main):005:0> r = LCG.new(time)
=> #
irb(main):006:0> r.next
=> 45940
irb(main):007:0> r.next
=> 1558831
irb(main):008:0> r.next
=> 1204687
irb(main):009:0> f = LCG.new(time)
=> #
irb(main):010:0> f.next
=> 45940
irb(main):011:0> f.next
=> 1558831
irb(main):012:0> f.next
=> 1204687

Based on the values a/b/m, the result will be the same for a given seed. This can be used to generate the same "random" number in two places and both sides can depend on getting the same result. This can be useful for encryption; although obviously, this algorithm isn't cryptographically secure.