# File lib/eymiha/math3/quaternion.rb, line 88
    def to_axis_angle
      half_angle = Math.acos(@real)
      sin_half_angle = Math.sin(half_angle)
      axis = (sin_half_angle.abs < 0.00000001)?
      Point3.new(1,0,0) : Point3.new(@axis).scale!(1.0/sin_half_angle)
      Quaternion.new(axis,2.0*half_angle)
    end