C ROTA      SOURCE    CHAT      05/01/13    03:04:57     5004           
      FUNCTION ROTA(S,CC,SS,CS,I)
C
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8 (A-H,O-Z)
C
      DIMENSION S(*)
C
      GO TO(1,2,3),I
C
    1 ROTA=S(1)*CC+2.D0*CS*S(4)+S(2)*SS
      GO TO 4
    2 ROTA=S(1)*SS-2.D0*CS*S(4)+S(2)*CC
      GO TO 4
    3 ROTA=CS*(S(2)-S(1))+S(4)*(CC-SS)
C
    4 RETURN
      END