SUBROUTINE MFFTC8(C,FAC)**   PURPOSE:*       ELEMENTARY GENTLEMAN-SANDE RADIX 5 STEP APPLIED TO A VECTOR-OF*       2-VECTORS-OF-COMPLEX C[IMS,NM [IVS,NV [IES,NE]]].*       SEE REF.[1] FOR NOTATIONS.*       THIS ROUTINE CAN BE USED ONLY BY ROUTINE MFFTDS, WHICH CONTROLS*       ITS OPERATION THROUGH THE MFFTPA COMMON**   DUMMY ARGUMENTS :**   C   ARRAY BEING FOURIER  TRANSFORMED*   FAC PHASE FACTORS, PREPARED BY MFFTP; NOT MODIFIED IN OUTPUT*      COMMON /MFFTPA/  IMS,IVS,IES,NM,NV,NE,MX,LX,MLIM,MSTEP,LLIM,LSTEP,     $ NUSTEP,IVLIM,ILIM,MD2LIM,LD2LIM      INTEGER NUSTEP      COMPLEX C(0:NUSTEP-1,0:4),FAC(0:*)      COMPLEX T1,T2,T3,T4,T5      REAL SIN72,RAD5D4,S36D72      PARAMETER (     $ SIN72 =  9.51056516295153572116439333E-1,     $ RAD5D4 =  5.59016994374947424102293417E-1,     $ S36D72 =  6.18033988749894848204586834E-1 )      IF(MX.NE.1)THEN            DO 200 LAM=0,LLIM,LSTEP              DO 190 IV=LAM,LAM+IVLIM,IVS                IMUF=0                IMUF2=NUSTEP                IMUF3=2*NUSTEP                IMUF4=3*NUSTEP                DO 180 IMU=IV,IV+ILIM                  T1=C(IMU,1)+C(IMU,4)                  T2=C(IMU,2)+C(IMU,3)                  T3=(C(IMU,1)-C(IMU,4))*SIN72                  T4=(C(IMU,2)-C(IMU,3))*SIN72                  T5=T1+T2                  T1=RAD5D4*(T1-T2)                  T2=C(IMU,0)-0.25*T5                  C(IMU,0)=C(IMU,0)+T5                  T5=T2+T1                  T2=T2-T1                  T1=T3+S36D72*T4                  T3=S36D72*T3-T4                  C(IMU,1)=(T5-CMPLX(-AIMAG(T1),REAL(T1)))*FAC(IMUF )                  C(IMU,4)=(T5+CMPLX(-AIMAG(T1),REAL(T1)))*FAC(IMUF4)                  C(IMU,2)=(T2-CMPLX(-AIMAG(T3),REAL(T3)))*FAC(IMUF2)                  C(IMU,3)=(T2+CMPLX(-AIMAG(T3),REAL(T3)))*FAC(IMUF3)                  IMUF=IMUF+1                  IMUF2=IMUF2+1                  IMUF3=IMUF3+1                  IMUF4=IMUF4+1  180           CONTINUE  190         CONTINUE200         CONTINUE        ELSE            DO 400 LAM=0,LLIM,LSTEP              DO 390 IV=LAM,LAM+IVLIM,IVS                DO 380 IMU=IV,IV+ILIM                  T1=C(IMU,1)+C(IMU,4)                  T2=C(IMU,2)+C(IMU,3)                  T3=(C(IMU,1)-C(IMU,4))*SIN72                  T4=(C(IMU,2)-C(IMU,3))*SIN72                  T5=T1+T2                  T1=RAD5D4*(T1-T2)                  T2=C(IMU,0)-0.25*T5                  C(IMU,0)=C(IMU,0)+T5                  T5=T2+T1                  T2=T2-T1                  T1=T3+S36D72*T4                  T3=S36D72*T3-T4                  C(IMU,1)=T5-CMPLX(-AIMAG(T1),REAL(T1))                  C(IMU,4)=T5+CMPLX(-AIMAG(T1),REAL(T1))                  C(IMU,2)=T2-CMPLX(-AIMAG(T3),REAL(T3))                  C(IMU,3)=T2+CMPLX(-AIMAG(T3),REAL(T3))380             CONTINUE390           CONTINUE400         CONTINUE        ENDIF      END