anchor.diff:        ICOUNT=0
         IDSDT=1
         DT=DT0
  -C
  +      IDEBUG = 4
  +C MWF ADD SANITY CHECK TO MAKE SURE POINT IS IN ELEMENT?
  +      
  +      CALL INTRP123(MAXEQ,MAXND,NEQ,NODE,XS,XW,DN_S,DJAC)
  +      DO I=1,NODE
  +         IF (DN_S(I).LT.-DN_SAFE.OR.DN_S(I).GT.1.0+DN_SAFE) THEN
  +            WRITE(6,*)'***PROBLEM ENTERING ELTRAK123  T= ',T,' DT= ',DT,
  +     &           ' I1= ',I1,' I2= ',I2,' I3= ',I3
  +            WRITE(6,*)'XS= ',(XS(II),II=1,NEQ)
  +            WRITE(6,*)'DN_S= ',(DN_S(II),II=1,NODE)
  +            DO II=1,NODE
  +               DO KK=1,NEQ
  +                  WRITE(6,*)'XW(',KK,',',II,')= ',XW(KK,II)
  +               ENDDO
  +            ENDDO
  +C            CALL EXIT(1)
  +         ENDIF
  +      ENDDO
     100 CONTINUE
  +C MWF DEBUG CATCH TOO SMALL TIME STEP
  +      IF (DABS(DT).LT.1.0D-10) THEN
  +         WRITE(6,*)'ELTRAK123 DT= ',DT,' TOO SMALL QUITTING'
  +         CALL EXIT(1)
  +      ENDIF
         ICOUNT=ICOUNT+1
         CALL RKCK_PT
        I    (MAXEQ,MAXND,NEQ,NODE, T,DT,T1,T2,
        I     XW,VT1W,VT2W,XS,
        M     AK1,AK2,AK3,AK4,AK5,AK6,XTEMP,
        O     XOUT5,XOUT4,XERR,DN_S)
  +      IF (IDEBUG.GT.1) THEN
   CMWF DEBUG
  -C      WRITE(6,*)'ELTRAK AFTER RKCK_PT T= ',T,' DT= ',DT,
  -C     &     ' T1= ',T1,' T2= ',T2
  -C      WRITE(6,*)'XS= ',(XS(I),I=1,NEQ)
  -C      WRITE(6,*)'DN_S= ',(DN_S(I),I=1,NODE)
  +         WRITE(6,*)'ELTRAK AFTER RKCK_PT T= ',T,' DT= ',DT,
  +     &     ' T1= ',T1,' T2= ',T2
  +         WRITE(6,*)'XS= ',(XS(I),I=1,NEQ)
  +         WRITE(6,*)'DN_S= ',(DN_S(I),I=1,NODE)
  +      ENDIF
   C
   C CHECK ERROR IN ALL THREE DIRECTIONS 
   C
  
positive.code: C IF THE ENDING LOCATION CAN BE CONSIDERED ON THE ELEMENT BOUNDARY
  C ==> NO NEED TO REDUCE TIMESTEP
  C
                IF(DABS(D2*DL).LE.ATOL)GOTO 150
  C
  C IF THE ENDING LOCATION IS TRULY OUTSIDE OF THE ELEMENT
  C ==> COMPUTE AN INTERPOLATION FACTOR
  C
                XSI=DMAX1(XSI,D12/D1)
              ENDIF
            ENDIF
    150   CONTINUE
  
negative.code: C        
        ELSEIF(RATIO.LE.1.0E0)THEN
  CMWF DEBUG
           IF (IDEBUG.GT.2) THEN
              WRITE(6,*)'ELTRAK AFTER ERROR SUCCESS T= ',T,' RATIO= ',
       &           RATIO
           ENDIF
  C
  C === EXAMINE THE COMPUTED ENDING LOCATION
  C
  C MWF WHAT IF FORCE SOME REDUCTION IF STEP OUTSIDE
  CMWF ORIG        
           XSI=0.0D0
           
          CALL INTRP123
       I      (MAXEQ,MAXND,NEQ,NODE, XOUT5, XW,
       O       DN,DJAC)
  