Bullshit::NormalDistribution

# File lib/bullshit.rb, line 869
    def initialize(mu = 0.0, sigma = 1.0)
      @mu, @sigma = mu.to_f, sigma.to_f
    end

# File lib/bullshit.rb, line 885
    def inverse_probability(p)
      case
      when p <= 0
        -1 / 0.0
      when p >= 1
        1 / 0.0
      when p == 0.5 # This is a bit sloppy, maybe improve this later.
        @mu
      else
        begin
          NewtonBisection.new { |x| probability(x) - p }.solve(nil, 1_000_000)
        rescue
          0 / 0.0
        end
      end
    end

# File lib/bullshit.rb, line 879
    def probability(x)
      0.5 * (1 + erf((x - @mu) / (@sigma * ROOT2)))
    end