class MoreMath::ChiSquareDistribution

def inverse_probability(p)

NormalDistribution for the probability +p+.
Returns the inverse cumulative probability value of the 
def inverse_probability(p)
  case
  when p <= 0, p >= 1
    0.0
  else
    begin
      bisect = NewtonBisection.new { |x| probability(x) - p }
      range = bisect.bracket 0.5..10
      bisect.solve(range, 1_000_000)
    rescue
      0 / 0.0
    end
  end
end