extern int otb_6s_csalbr_(
  otb_6s_doublereal *xtau,
  otb_6s_doublereal *xalb
  );
extern otb_6s_doublereal otb_6s_fintexp3_(
  otb_6s_doublereal *xtau
  );
extern otb_6s_doublereal otb_6s_fintexp1_(
  otb_6s_doublereal *xtau
  );
