Module: Capricious::PRNG

Included in:
Erlang, Exponential, Normal, Poisson, Uniform
Defined in:
lib/capricious/generic_prng.rb

Overview

Base mixin for distribution simulators. Manages an underlying PRNG and optional statistics. Mixing =PRNG= in to a simulator class will define

next= and =reset= methods as well as =@aggregate= and =@seed= attributes

and a =@prng= instance variable. Simulator classes must define a

next_value= method that returns a value in the given distribution and

should define =expected_mean= and =expected_variance= methods or attributes.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



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# File 'lib/capricious/generic_prng.rb', line 60

def self.included(base)
  base.class_eval do
    attr_reader :aggregate, :seed
  end
end

Instance Method Details

#initialize(seed = nil, policy = MWC5, keep_stats = false) ⇒ Object

Takes a seed, a policy, and whether or not to keep statistics in the

aggregate= attribute of the distribution object. If a simulator class

overrides =initialize=, it must call =prng_initialize= from within its

initialize= method.



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# File 'lib/capricious/generic_prng.rb', line 37

def initialize(seed=nil, policy=MWC5, keep_stats=false)
  prng_initialize(seed, policy, keep_stats)
end

#next ⇒ Object

Returns the next value from this simulator.



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# File 'lib/capricious/generic_prng.rb', line 48

def next
  val = next_value
  @aggregate << val if @aggregate
  val
end

#prng_initialize(seed = nil, policy = MWC5, keep_stats = false) ⇒ Object 



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# File 'lib/capricious/generic_prng.rb', line 41

def prng_initialize(seed=nil, policy=MWC5, keep_stats=false)
  @prng = policy.new_with_seed(seed)
  @seed = @prng.seed
  @aggregate = SampleSink.new if keep_stats
end

#reset(seed = nil) ⇒ Object

Resets the state of the underlying value.



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# File 'lib/capricious/generic_prng.rb', line 55

def reset(seed=nil)
  @prng.reset(seed)
  @aggregate = SampleSink.new if @aggregate
end