*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1996/04/01 15:02:18  mclareni
* Mathlib gen
*
*
#include "gen/pilot.h"
      SUBROUTINE ELANAL (MP,N,IBCX,POT,POTW,POTE,POTS,POTN)
      COMMON/FW1/W1(774)/FW2/W2(100)
      DIMENSION POT(MP,N)
      DIMENSION POTW(N),POTE(N),POTS(MP),POTN(MP)
      M=MP-1
      MD=MP+M
      AX=(1./LOG10(2.))+.01
      XM=M
      AM=AX*LOG10(XM)
      IM=INT(AM)
      IF(IBCX.EQ.4) GO TO 400
C   THE RFT ROUTINE IS A MODIFIED
C   VERSION OF HOCKNEY FAST FOURIER
C   TRANSFORM PACKAGE AND CORRESPONDS TO
C   ISELIN LIBRARY PROGRAM D 700
C
      CALL RFT(IM,POTS,1,W1(2*MP+1),1,IBCX)
      CALL RFT(IM,POTN,1,W1(3*MP+1),1,IBCX)
      DO 1 J=1,N
 1    CALL RFT(IM,POT(1,J),1,POT(1,J),1,IBCX)
      RETURN
C
C   THE MFT ROUTINE IS USED FOR
C   THE FOURTH TYPE OF BOUNDARY
C   CONDITION ALONG X
C
 400  CALL MFT(MP,MD,POTS,W1(2*MP+1),W1(4*MP+1),1)
      CALL MFT(MP,MD,POTN,W1(3*MP+1),W1(4*MP+1),1)
C
      DO 2 J=1,N
      DO 3 I=1,MP
 3    W1(I)=POT(I,J)
C
      CALL MFT(MP,MD,W1,W1(MP+1),W1(4*MP+1),1)
C
      DO 4 I=1,MP
 4    POT(I,J)=W1(I+MP)
 2    CONTINUE
      RETURN
      END