Class: Rubystats::UniformDistribution

Inherits:
ProbabilityDistribution show all
Includes:
SpecialMath
Defined in:
lib/rubystats/uniform_distribution.rb

Constant Summary

Constants included from NumericalConstants

NumericalConstants::EPS, NumericalConstants::GAMMA, NumericalConstants::GAMMA_X_MAX_VALUE, NumericalConstants::GOLDEN_RATIO, NumericalConstants::LOG_GAMMA_X_MAX_VALUE, NumericalConstants::MAX_FLOAT, NumericalConstants::MAX_ITERATIONS, NumericalConstants::MAX_VALUE, NumericalConstants::PRECISION, NumericalConstants::SQRT2, NumericalConstants::SQRT2PI, NumericalConstants::TWO_PI, NumericalConstants::XMININ

Instance Attribute Summary

Attributes included from SpecialMath

#log_beta_cache_p, #log_beta_cache_q, #log_beta_cache_res, #log_gamma_cache_res, #log_gamma_cache_x

Instance Method Summary collapse

Methods included from SpecialMath

#beta, #beta_fraction, #complementary_error, #error, #gamma, #gamma_fraction, #gamma_series_expansion, #incomplete_beta, #incomplete_gamma, #log_beta, #log_gamma, #orig_gamma

Methods inherited from ProbabilityDistribution

#cdf, #check_range, #find_root, #get_factorial, #icdf, #mean, #pdf, #rng, #variance

Methods included from ExtraMath

#binomial

Constructor Details

#initialize(lower = 0.0, upper = 1.0) ⇒ UniformDistribution

Constructs a uniform distribution (defaults to zero lower and unity upper bound).



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# File 'lib/rubystats/uniform_distribution.rb', line 9

def initialize(lower=0.0, upper=1.0)
  lower,upper = upper,lower if lower > upper
  @lower = lower.to_f
  @upper = upper.to_f
  @pdf_denominator = 1.0 / (@upper - @lower)
  @use_last = nil
end

Instance Method Details

#get_mean ⇒ Object

Returns the mean of the distribution



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# File 'lib/rubystats/uniform_distribution.rb', line 18

def get_mean 
  return 0.5*(@lower + @upper)
end

#get_standard_deviation ⇒ Object

Returns the standard deviation of the distribution



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# File 'lib/rubystats/uniform_distribution.rb', line 23

def get_standard_deviation
  return Math.sqrt(get_variance)
end

#get_variance ⇒ Object

Returns the variance of the distribution



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# File 'lib/rubystats/uniform_distribution.rb', line 28

def get_variance
  return 1.0/12.0 * (@upper-@lower)**2
end