subroutine rtll(tlmd,tphd,tlm0d,ctph0,stph0,almd,aphd)
c
c *** Rotate eta lat, lon (tphd, tlmd) to geographical lat, lon (aphd, almd).
c     All calculations are done in degrees.
c
      implicit none
c
      real*4 tlmd,tphd 
     .      ,tlm0d,ctph0,stph0
     .      ,almd,aphd,cph
     .      ,stph,ctph,ctlm,stlm
     .      ,saphd,salmd
CTO
      REAL*4,PARAMETER :: d2r=.017453293
CTO

c_______________________________________________________________________________
c
      stph=sind(tphd)
      ctph=cosd(tphd)
      ctlm=cosd(tlmd)
      stlm=sind(tlmd)
c
      saphd=stph0*ctph*ctlm+ctph0*stph
crr
      if(saphd.gt. 1.)saphd= 1.
      if(saphd.lt.-1.)saphd=-1.
crr
CTO      aphd=asind(saphd)
      aphd=asin(saphd)
      aphd=aphd*(1./d2r)
c
      cph=cosd(aphd)
      salmd=stlm*ctph/cph
crr
      if(salmd.gt. 1.) salmd= 1.
      if(salmd.lt.-1.) salmd=-1.
crr
CTO      almd=tlm0d+asind(salmd)
      almd=asin(salmd)
      almd=almd*(1./d2r)
      almd=almd+tlm0d
c
      return
      end