c990408
      SUBROUTINE FFT991(A,TRIGS,IFAX,INC,JUMP,N,LOT,ISIGN)
C      SUBROUTINE FFT991(A,WORKX,TRIGS,IFAX,INC,JUMP,N,LOT,ISIGN)
C      SUBROUTINE FFT991(A,WORK,TRIGS,IFAX,INC,JUMP,N,LOT,ISIGN)
C=======================================================================
C&&& INC=1 IS ASSUMED ***
C&&& INPUT/OUTPUT HAS A DIMENSION OF N*LOT
C&&& A & WORK SHOULD HAVE A DIMENSION OF JUMP*LOT
C&&& CREATED ON JUN/21/88 BY N.SATO
C=======================================================================
      PARAMETER(NFFT=256)

c990408
c      DIMENSION WORKX(N, 1920)

      DIMENSION A(N,LOT),WORK(JUMP,NFFT),TRIGS(N),IFAX(*)
      DIMENSION WORK2(N*JUMP*NFFT)

      IF(ISIGN .EQ. 1) GO TO 2000
      DO L0=1,LOT,NFFT
      LOTL=MIN(NFFT,LOT-L0+1)

      DO 100 L=1,LOTL
      DO 100 I=1,N
      WORK(I,L)=A(I,L+L0-1)
  100 CONTINUE
C
C GRID TO WAVE
C
C   X(0),...,X(N-1) ===> A(0),A(1),B(1),...,A(N/2-1),B(N/2-1),A(N/2)
C
          CALL RFFTFM (N,INC,JUMP,LOTL, WORK, TRIGS,IFAX, WORK2 )
C
C   A(0),A(1),B(1),... ===> A(0),B(0),A(1),B(1),...
C
*VOPTION NOFVAL
      DO 200 L=1,LOTL
      DO 200 I=3,N
      A(I,L+L0-1)=WORK(I-1,L)
  200 CONTINUE
      DO 240 L=1,LOTL
      A(1,L+L0-1)=WORK(1,L)
      A(2,L+L0-1)=0.0
  240 CONTINUE
      ENDDO
        RETURN
C
C  WAVE TO GRID
C
C    A(0),B(0),A(1),B(1),... ===> A(0),A(1),B(1),...
C
 2000 CONTINUE
      DO L0=1,LOT,NFFT
      LOTL=MIN(NFFT,LOT-L0+1)

      DO 300 L=1,LOTL
      DO 300 I=3,N
      WORK(I-1,L)=A(I,L+L0-1)
  300 CONTINUE
      DO 340 L=1,LOTL
cnec  DO 340 L=1,LOT
      WORK(1,L)=A(1,L+L0-1)
      WORK(N,L)=0.0
  340 CONTINUE
C
C    A(0),A(1),B(1)...A(N/2-1),B(N/2-1),A(N/2) ===> X(0)...X(N-1)
C
          CALL RFFTBM (N,INC,JUMP,LOTL, WORK, TRIGS,IFAX, WORK2)

      DO 400 L=1,LOTL
      DO 400 I=1,N
      A(I,L+L0-1)=WORK(I,L)
  400 CONTINUE
      ENDDO
C
      RETURN
      END SUBROUTINE FFT991