!CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
!                                                                       
!   FFTPACK 5.0                                                         
!                                                                       
!   Authors:  Paul N. Swarztrauber and Richard A. Valent                
!                                                                       
!   $Id: r1f2kf.f,v 1.2 2004/06/15 21:29:20 rodney Exp $                
!                                                                       
!CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
                                                                        
      SUBROUTINE R1F2KF (IDO,L1,CC,IN1,CH,IN2,WA1) 
      REAL       CH(IN2,IDO,2,L1) ,CC(IN1,IDO,L1,2) , WA1(IDO) 
!                                                                       
      DO 101 K=1,L1 
         CH(1,1,1,K) = CC(1,1,K,1)+CC(1,1,K,2) 
         CH(1,IDO,2,K) = CC(1,1,K,1)-CC(1,1,K,2) 
  101 END DO 
      IF (IDO-2) 107,105,102 
  102 IDP2 = IDO+2 
      DO 104 K=1,L1 
         DO 103 I=3,IDO,2 
            IC = IDP2-I 
            CH(1,I,1,K) = CC(1,I,K,1)+(WA1(I-2)*CC(1,I,K,2)-            &
     &       WA1(I-1)*CC(1,I-1,K,2))                                    
            CH(1,IC,2,K) = (WA1(I-2)*CC(1,I,K,2)-WA1(I-1)*              &
     &       CC(1,I-1,K,2))-CC(1,I,K,1)                                 
            CH(1,I-1,1,K) = CC(1,I-1,K,1)+(WA1(I-2)*CC(1,I-1,K,2)+      &
     &       WA1(I-1)*CC(1,I,K,2))                                      
            CH(1,IC-1,2,K) = CC(1,I-1,K,1)-(WA1(I-2)*CC(1,I-1,K,2)+     &
     &       WA1(I-1)*CC(1,I,K,2))                                      
  103    CONTINUE 
  104 END DO 
      IF (MOD(IDO,2) .EQ. 1) RETURN 
  105 DO 106 K=1,L1 
         CH(1,1,2,K) = -CC(1,IDO,K,2) 
         CH(1,IDO,1,K) = CC(1,IDO,K,1) 
  106 END DO 
  107 RETURN 
      END