Class: EnvelopeAlloc::RandomGaussian

Inherits:
Object
  • Object
show all
Defined in:
lib/envelope_alloc/gaussian.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(mean, stddev, rand_helper = lambda {Kernel.rand}) ⇒ RandomGaussian

Returns a new instance of RandomGaussian.



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# File 'lib/envelope_alloc/gaussian.rb', line 13

def initialize(mean, stddev, rand_helper = lambda {Kernel.rand})
  @rand_helper = rand_helper
  @mean = mean
  @stddev = stddev
  @valid = false
  @next = 0
end

Class Method Details

.gaussian(mean, stddev, rand) ⇒ Object 



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# File 'lib/envelope_alloc/gaussian.rb', line 4

def self.gaussian(mean, stddev, rand)
  rho = Math.sqrt(-2 * Math.log(1 - rand.call))
  scale = stddev * rho
  theta = 2 * Math::PI * rand.call
  x = mean + scale * Math.cos(theta)
  y = mean + scale * Math.sin(theta)
  [x, y]
end

Instance Method Details

#rand ⇒ Object 



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# File 'lib/envelope_alloc/gaussian.rb', line 21

def rand
  if @valid
    @valid = false
    @next
  else
    @valid = true
    x, y = self.class.gaussian(@mean, @stddev, @rand_helper)
    @next = y
    x
  end
end