SUBROUTINE PASSF3 (IDO,L1,CC,CH,WA1,WA2)
      DIMENSION       CC(IDO,3,L1)           ,CH(IDO,L1,3)           ,
     1                WA1(1)     ,WA2(1)
      DATA TAUR,TAUI /-.5,-.866025403784439/
      IF (IDO .NE. 2) GO TO 102
      DO 101 K=1,L1
         TR2 = CC(1,2,K)+CC(1,3,K)
         CR2 = CC(1,1,K)+TAUR*TR2
         CH(1,K,1) = CC(1,1,K)+TR2
         TI2 = CC(2,2,K)+CC(2,3,K)
         CI2 = CC(2,1,K)+TAUR*TI2
         CH(2,K,1) = CC(2,1,K)+TI2
         CR3 = TAUI*(CC(1,2,K)-CC(1,3,K))
         CI3 = TAUI*(CC(2,2,K)-CC(2,3,K))
         CH(1,K,2) = CR2-CI3
         CH(1,K,3) = CR2+CI3
         CH(2,K,2) = CI2+CR3
         CH(2,K,3) = CI2-CR3
  101 CONTINUE
      RETURN
  102 DO 104 K=1,L1
         DO 103 I=2,IDO,2
            TR2 = CC(I-1,2,K)+CC(I-1,3,K)
            CR2 = CC(I-1,1,K)+TAUR*TR2
            CH(I-1,K,1) = CC(I-1,1,K)+TR2
            TI2 = CC(I,2,K)+CC(I,3,K)
            CI2 = CC(I,1,K)+TAUR*TI2
            CH(I,K,1) = CC(I,1,K)+TI2
            CR3 = TAUI*(CC(I-1,2,K)-CC(I-1,3,K))
            CI3 = TAUI*(CC(I,2,K)-CC(I,3,K))
            DR2 = CR2-CI3
            DR3 = CR2+CI3
            DI2 = CI2+CR3
            DI3 = CI2-CR3
            CH(I,K,2) = WA1(I-1)*DI2-WA1(I)*DR2
            CH(I-1,K,2) = WA1(I-1)*DR2+WA1(I)*DI2
            CH(I,K,3) = WA2(I-1)*DI3-WA2(I)*DR3
            CH(I-1,K,3) = WA2(I-1)*DR3+WA2(I)*DI3
  103    CONTINUE
  104 CONTINUE
      RETURN
      END