def comp_r_bias_prec
      gamma = comp_gamma_bp
      phi   = comp_phi_bp
      psi   = comp_psi_bp
      r = r_z(gamma)
      r = r_x(phi,   r)
      r = r_z(-psi,  r)
      r = r_x(-@eps, r)
      return r
    rescue => e
      raise
    end
def comp_r_bias_prec
      gamma = comp_gamma_bp
      phi   = comp_phi_bp
      psi   = comp_psi_bp
      r = r_z(gamma)
      r = r_x(phi,   r)
      r = r_z(-psi,  r)
      r = r_x(-@eps, r)
      return r
    rescue => e
      raise
    end
=========================================================================
 Bias + Precession 変換行列

 * IAU 2006 (Fukushima-Williams 4-angle formulation) 理論

 @param:  <none>
 @return: r  (変換行列)
=========================================================================