C	THIS IS A SAMPLE DRIVER TO SHOW SOME OF THE FEATURES OF THE FFT
C  ROUTINE FFTBA2.
C  TWO SIGNALS, BOTH 50% DUTY-CYCLE SQUARE WAVES ARE GENERATED, TRANSFORMED,
C  INVERSE TRANSFORMED, AND FOLDED. THE FIRST AND LAST 8 VALUES FOR BOTH THE
C  REAL AND IMAGINARY VECTORY ARE PRINTED AFTER EACH OPERATION.
C	
C	THE FIRST SQUARE WAVE IS CENETERD ABOUT T=0 AND IS THEREFORE AN
C  EVEN FUNCTION GENERATING ONLY COSINE TERMS. THE SECOND SQUARE WAVE HAS
C  ITS NEGATIVE TO POSITIVE TRANSISTION AT T=0 AND IS THEREFORE AN ODD
C  FUNCTION GENERATING ONLY SINE TERMS.
C  THE XR(1) TERM OF THE TRANSFORMED VECTORS IS THE DC TERM AND THE XI(1) TERM
C  OF THE TRANSFORMED VECTORS IS ALWAYS IDENTICALLY ZERO.
C
C	THE CALL TO FFTBA2S IS:
C	CALL FFTBA2(XR,XI,N,L,KUNS) WHERE
C	XR = THE REAL COMPONENT OF THE SIGNAL OR THE COEFFICIENTS OF THE
C	     COSINE TERMS.
C	XI = THE IMAGINARY COMPONENT OF THE SIGNAL OR THE COEFFICIENTS OF
C	     THE SINE TERMS.
C	N = THE LENGTH OF VECTORS XR AND XI. N MUST BE A POWER OF 2 .
C	L  DETERMINS IF THE TRANSFORM IS FORWARD L > 0, OR INVERSE L < 0 ;
C	   IF L = 0, NO TRANSFORMATION TAKES PLACE BUT UNSCRAMBLING MAY TAKE
C	   PLACE DETERMINED BY THE VALUE OF KUNS.
C	KUNS CONTROLS UNSCRAMBLING OF THE TRANSFORMED DATA. IF KUNS = 0, THEN
C	     NO UNSCRAMBLING TAKES PLACE. NOTE THAT EACH TIME DATA IS EITHER
C	     FORWARD OR INVERSE TRANSFORMED, THE VECTORS ARE SCRAMBLED. THE
C	     THE DYADIC SCRAMBLING IS ITS OWN INVERSE; HENCE TWO SUCESSIVE
C	     SCRAMBLINGS (UNSCRAMBLINGS) CANCEL EACH OTHER.	
	DIMENSION XR(4096),XI(4096)
	REAL *8 VOT(2),VTT(2),DSW(2),DRR,DII
	LOGICAL *1 IJK,ISW
	DATA  VOT/'ORIGINAL','   '/,VTT/'TRANSFOR','MED'/,
	1DRR/' REAL '/,DII/' IMAG. '/,DSW/'CENTER',' START'/
	DATA XI/4096*0./
	IJK=.FALSE.
	ISW=IJK
	KSW=1
	N=4096
	KK=8
	LL=N-KK+1
8	IF(ISW)GOTO 33
	DO 10 I=1,1024
10	XR(I)=1.
	DO 11 I=1025,3072
11	XR(I)=0.
	DO 12 I=3073,4096
12	XR(I)=1.
	GOTO 41
33	DO 20 I=1,2048
	XR(I)=1.
20	XI(I)=0.
	DO 21 I=2049,4096
	XR(I)=0.
21	XI(I)=0.
	KSW=2
41	TYPE 899,DSW(KSW)
899	FORMAT('1THIS SAMPLE IS FOR A SQUARE WAVE OF UNITY AMPLITUDE FROM ',
	1'ZERO TO ONE,'/' HENCE THE PULSE HAS A DC COMPONENT OF 0.5 .'/
	2' THE DUTY CYCLE IS 50% AND THE PULSE IS DEFINED ',
	3'WITH 4096 SAMPLES'/' WITH THE ',A6,' OF THE POSITIVE HALF CYCLE ',
	1'AT T = 0'/)
	ICNT=1
	IFR=1
	TYPE 900,KK,VOT(1),VOT(2),DRR
	CALL XPRNT(XR,XI,N,KK,LL,1)
	TYPE 900,KK,VOT(1),VOT(2),DII
	CALL XPRNT(XR,XI,N,KK,LL,-1)
1	CALL FFTBA2(XR,XI,N,IFR,1)
	IF(IJK)CALL FOLDFT(XR,XI,N,-1)
	TYPE 900,KK,VTT,DRR
900	FORMAT('0THE FIRST AND LAST',I5,' TERMS OF THE ',A8,A3,
	1A7'VECTOR:')
	CALL XPRNT(XR,XI,N,KK,LL,1)
	TYPE 900,KK,VTT,DII
	CALL XPRNT(XR,XI,N,KK,LL,-1)
	IF(IJK)TYPE 999
999	FORMAT(' NOTE THAT NOW XR(1) CONTAINS A0, TWICE THE DC COMPONENT ',
	1'AND NOT A0/2')
	IF(IJK)GOTO 51
	IFR=-IFR
	ICNT=ICNT+1
	IF(ICNT.GT.2)GO TO 2
	TYPE 901
901	FORMAT('0THE TRANSFORMED DATA WILL NOW BE INVERSE TRANSFORMED AND ',
	1'PRINTED')
	GOTO 1
2	TYPE 998
998	FORMAT('1THE USE OF THE SUBROUTINE FOLDFT TO GENERATE THE FOURIER ',
	1'COEFFICIENTS'/'  WITH ITYPE = -1')
	IJK=.TRUE.
	GOTO 1
51	IF(ISW)CALL EXIT
	ISW=.TRUE.
	IJK=.FALSE.
	GOTO 8
	END
	SUBROUTINE XPRNT(XR,XI,N,KK,LL,IC)
	DIMENSION XR(N),XI(N)
	IF(IC.GT.0)TYPE 909,(I,XR(I),I=1,KK)
	IF(IC.GT.0)TYPE 909,(I,XR(I),I=LL,N)
	IF(IC.LT.0)TYPE 909,(I,XI(I),I=1,KK)
	IF(IC.LT.0)TYPE 909,(I,XI(I),I=LL,N)
909	FORMAT(4(1H ,(I4,1PE11.3,5X)))
	RETURN
	END