extern otb_6s_doublereal ro_1_otb_6s__(
  otb_6s_doublereal *theta_i__,
  otb_6s_doublereal *phi_i__,
  otb_6s_doublereal *theta_e__,
  otb_6s_doublereal *phi_e__
  );
extern otb_6s_doublereal gamma_f_otb_6s__(
  otb_6s_doublereal *theta_p__,
  otb_6s_doublereal *phi_p__,
  otb_6s_doublereal *theta,
  otb_6s_doublereal *phi
  );
extern otb_6s_doublereal otb_6s_geo_(
  otb_6s_doublereal *theta_i__,
  otb_6s_doublereal *phi_i__,
  otb_6s_doublereal *theta_e__,
  otb_6s_doublereal *phi_e__
  );
extern otb_6s_doublereal otb_6s_h_(
  otb_6s_doublereal *xl,
  otb_6s_doublereal *xli
  );
extern otb_6s_doublereal g_f_otb_6s__(
  otb_6s_doublereal *theta
  );
extern otb_6s_doublereal otb_6s_psi_(
  otb_6s_doublereal *theta,
  otb_6s_doublereal *xt
  );
extern otb_6s_doublereal otb_6s_gl_(
  otb_6s_doublereal *theta
  );
extern int otb_6s_gauleg_(
  otb_6s_doublereal *x1,
  otb_6s_doublereal *x2,
  otb_6s_doublereal *x,
  otb_6s_doublereal *w,
  otb_6s_integer *n
  );
extern int otb_6s_solve_(
  otb_6s_doublereal *theta_i__
  );
extern int otb_6s_lad_(
  
  );
