SUBROUTINE MFFTA8(C,FAC)**   PURPOSE:*       ELEMENTARY GENTLEMAN-SANDE RADIX-2 STEP APPLIED TO A VECTOR-OF-*       2-VECTORS-OF-COMPLEX [IMS,NM [IVS,NV [IES,NE]]], OPTIMIZED FOR*       SMALL NE MATRICES.*       SEE REF.[1] FOR NOTATIONS.*       THIS ROUTINE CAN BE USED ONLY BY ROUTINE MFFTDM, WHICH CONTROLS*       ITS OPERATION THROUGH COMMON MFFTPA.**   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-1,0:1),FAC(0:*),T0*      IF (MX.NE.1) THEN*      DO 200 LAM=0,LLIM,LSTEP        DO 150 IV=LAM,LAM+IVLIM,IVS          IMUF=0          DO 100 IMU=IV,IV+ILIM            T0=C(IMU,0)            C(IMU,0)=T0+C(IMU,1)            C(IMU,1)=(T0-C(IMU,1))*FAC(IMUF)            IMUF=IMUF+1100       CONTINUE150      CONTINUE200   CONTINUE*      ELSE        DO 400 LAM=0,LLIM,LSTEP          DO 350 IV=LAM,LAM+IVLIM,IVS            DO 300 IMU=IV,IV+ILIM            T0=C(IMU,0)            C(IMU,0)=T0+C(IMU,1)            C(IMU,1)=T0-C(IMU,1) 300        CONTINUE 350      CONTINUE 400    CONTINUE      ENDIF*      END