lib/statistical/rng/laplace.rb
require 'statistical/distribution/laplace'
module Statistical
module Rng
# Companion RNG class for the continuous uniform distribution. Requires a
# distrbution object of the corresponding distribution
#
# @author Vaibhav Yenamandra
#
# @attr_reader [Numeric] scale Scale parameter of the Laplace distribution.
# @attr_reader [Numeric] location Location parameter to determine where the
# distribution is centered / where the mean lies at
class Laplace
attr_reader :generator, :scale, :location
def initialize(dobj = nil, seed = Random.new_seed)
unless dobj.nil? || dobj.is_a?(Statistical::Distribution::Laplace)
raise TypeError,
"Expected Distribution object or nil, found #{dobj.class}"
end
dobj = Statistical::Distribution::Laplace.new if dobj.nil?
@generator = Random.new(seed)
@scale = dobj.scale
@location = dobj.location
@sdist = dobj
end
# Return the next random number from the sequence
#
# @return next random number in the sequence
def rand
return @sdist.quantile(@generator.rand)
end
# Compare against another rng to see if they are the same
#
# @return true if and only if, source distributions are the same and the
# prng has the same initial state
def eql?(other)
return other.is_a?(self.class) &&
other.generator == @generator &&
other.location == @location &&
other.scale == @scale
end
# Return the type of the source distribution
#
# @return source distribution's type
def type
@sdist.class
end
alias :== :eql?
private :eql?
end
end
end