atan

# File lib/cmath.rb, line 271
  def atan(z)
    begin
      if z.real?
        atan!(z)
      else
        1.0.i * log((1.0.i + z) / (1.0.i - z)) / 2.0
      end
    rescue NoMethodError
      handle_no_method_error
    end
  end