anchor.diff:       O         IDSDT,XPT,TPT,I1,I2,I3)
   CMWF          NPATH(IPT)=KPATH
   C
  +          IF(IVERBOSE.GT.2) THEN
   C MWF DEBUG
  -C          WRITE(LU_O,*)' AFTER I1.NE.0 ELTRACK ELEMENT LOOP T= '
  -C     &         ,T,' IDSDT= ',IDSDT,' TPT= ',TPT(IPT),' IPT= ',IPT
  -C     &         ,' M= ',M
  -C          WRITE(LU_O,*)' I1= ',I1,' I2= ',I2,' I3= ',I3
  -C          DO K=1,NEQ
  -C             WRITE(LU_O,*)' XPT(',K,',',IPT,')= ',XPT(K + IPT*MAXEQ)
  -C          ENDDO
  +             WRITE(LU_O,*)' AFTER I1.NE.0 ELTRACK ELEMENT LOOP T= '
  +     &            ,T,' IDSDT= ',IDSDT,' TPT= ',TPT(IPT),' IPT= ',IPT
  +     &         ,' M= ',M
  +             WRITE(LU_O,*)' I1= ',I1,' I2= ',I2,' I3= ',I3
  +             DO K=1,NEQ
  +                WRITE(LU_O,*)' XPT(',K,',',IPT,')= ',
  +     &               XPT(K+(IPT-1)*MAXEQ)
  +             ENDDO
  +          ENDIF
             IF(IDSDT.EQ.-1)THEN
               MPT(IPT)=M
   C 0 -- INTERIOR
  
positive.code: C CONDUCT TRACKING WITHIN ELEMENT M
  C
  C REMOVE MAXPT,MAXPATH,KPATH ARGS
                  CALL ELTRAK123A
       I            (MAXEQ,MAXND,NPT,NEQ,NODE,
       I             IPT, T1,T2, DEQ, DN_SAFE,
       I             ZEROTOL,IDVT,
  
negative.code: C     HAVE TO TREAT AS FLAT ARRAY, SINCE MAY BE DIFFERENT SHAPES IN PYTHON (q, versus ebqe)
  C     ASSUME MPT,TPT SET BY CALLING CODE 
  CMWF DEBUG
        IF (IVERBOSE.GT.0) THEN
           WRITE(LU_O,*)'ENTERING PT123A'
           WRITE(LU_O,*)'NNP= ',NNP,' NEL= ',NEL,' NNDE= ',NNDE,' NEQ= ',
       &     NEQ,' NPT= ',NPT,' IBF= ',IBF,' LU_O= ',LU_O, ' ATOL= ',
       &     ATOL,' RTOL= ',RTOL, ' SF= ',SF, 'DN_SAFE= ',DN_SAFE
        ENDIF
        DO IPT=1,NPT
  
           IF(IVERBOSE.GT.1) THEN
  CMWF DEBUG
              WRITE(LU_O,*)'T_I(',IPT,')= ',T_I(IPT),
       &           ' TPT(',IPT,')= ',TPT(IPT)
           ENDIF
           DO I=1,NEQ
              XS(I)=X_I(I + MAXEQ*(IPT-1))
              XPT(I + MAXEQ*(IPT-1))=XS(I)
              IF(IVERBOSE.GT.1) THEN
  CMWF DEBUG
                 WRITE(LU_O,*)'X_I(',I,',',IPT,')= ',X_I(I+MAXEQ*(IPT-1)),
       &              ' XPT(',I,',',IPT,')= ',XPT(I + MAXEQ*(IPT-1))
              ENDIF
           ENDDO
        ENDDO
  C
  C =================== START PT USING ADAPTIVE RK ====================
  