      SUBROUTINE set_levels_shade_fill (status)
	
*
*
*  This software was developed by the Thermal Modeling and Analysis
*  Project(TMAP) of the National Oceanographic and Atmospheric
*  Administration's (NOAA) Pacific Marine Environmental Lab(PMEL),
*  hereafter referred to as NOAA/PMEL/TMAP.
*
*  Access and use of this software shall impose the following
*  obligations and understandings on the user. The user is granted the
*  right, without any fee or cost, to use, copy, modify, alter, enhance
*  and distribute this software, and any derivative works thereof, and
*  its supporting documentation for any purpose whatsoever, provided
*  that this entire notice appears in all copies of the software,
*  derivative works and supporting documentation.  Further, the user
*  agrees to credit NOAA/PMEL/TMAP in any publications that result from
*  the use of this software or in any product that includes this
*  software. The names TMAP, NOAA and/or PMEL, however, may not be used
*  in any advertising or publicity to endorse or promote any products
*  or commercial entity unless specific written permission is obtained
*  from NOAA/PMEL/TMAP. The user also understands that NOAA/PMEL/TMAP
*  is not obligated to provide the user with any support, consulting,
*  training or assistance of any kind with regard to the use, operation
*  and performance of this software nor to provide the user with any
*  updates, revisions, new versions or "bug fixes".
*
*  THIS SOFTWARE IS PROVIDED BY NOAA/PMEL/TMAP "AS IS" AND ANY EXPRESS
*  OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
*  ARE DISCLAIMED. IN NO EVENT SHALL NOAA/PMEL/TMAP BE LIABLE FOR ANY SPECIAL,
*  INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
*  RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
*  CONTRACT, NEGLIGENCE OR OTHER TORTUOUS ACTION, ARISING OUT OF OR IN
*  CONNECTION WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE. 
*
*
* V630  *acm* 9/09 Introduction of syntax for variance-based and histogram levels
* V631  *acm*10/09 Fix bug 1704: LEVELS=xD was incorrect.
* V663  *acm* 5/10 Fix bug 1744: hang if /LEVELS=v and all missing data.
* V68  *acm* 1/12  changes for double-precision ferret, single-precision pplus
* V697 *acm* 12/15 Fix ticket 2326: single level plus (inf) and/or (-inf)
* V698 *acm*  2/16 Send info that the levels are from a histogram to setlab_syms
* V720 *acm*  7/17 Ticket 2250: small-valued data caused an error computing number
*                  of interval-edges NLEV2
* V740 *acm*  2/18 Tweak for issue 1858: labels on contour lines for auto-generated 
*                  integer levels got unneeded digit after decimal point
* V74+  *acm* 3/18 Issue 1607.  /KEY=centerlab
*         For centered labels draw the plot so that the levels are describing 
*         the middle of the colors not the contour lines between colors.
*         Interpolate /LEVELS values to obtain new edge-values for the contours
*         and patch-edges

	include		'parampl5_dat.decl'
	include		'PARAMPL5.DAT'
	include		'axis_inc.decl'
	include		'AXIS.INC'
	include		'plt_inc.decl'
	include		'PLT.INC'
	include		'miss_inc.decl'
	include		'MISS.INC'
	include		'hd_inc.decl'
	include		'HD.INC'
	include		'cont_inc.decl'
	include		'CONT.INC'
        include         'errmsg.parm'
        include         'shade_vars.cmn'
	
* argument declarations
	INTEGER		status

* local declarations
	REAL		dz, fm, znp, zmp, dzmax, del
	INTEGER		m, jj
        LOGICAL		TM_FPEQ_SNGL, isinf, redo

        EXTERNAL range

	status = ferr_ok
	lev_str = 'none'
	IF (USE_HIST) lev_str = 'histogram'

	znp = 0.
	zmp = 0.
C       
C       IAUTOC = 1 means: compute levels from input data and number
C                         of levels

	IF (IAUTOC.EQ.1) THEN

	   IF (ZMIN.EQ.ZMAX) THEN

C             NLEV2=0 is the code in pplmod_plotz
	      NLEV2=1
              zlev(1) = zmin

	   ELSE IF (ZMIN .GT. CMZGE .AND. ZMAX .LE. CMZLE) THEN  ! all missing

C             NLEV2=0 is the code in pplmod_plotz
	      NLEV2=1
              zlev(1) = zmin

	   ELSE
C       
C       If set_delta is .true. the delta value has been set
C       elsewhere and we should calculate the max and min values
C       of the range based on this delta.
C       (This portion stolen from RANGE)

	      if (set_delta) then 

		 dz = delta
C       
C       CALCULATE THE MINIMUM VALUE OF THE RANGE
C       
		 FM = (zmin) / DZ
		 M = IFIX(FM)
		 IF (FM .LT. 0.0) M = M - 1
		 znp = DZ * FLOAT(M)
C       
C       CALCULATE THE MAXIMUM VALUE OF THE RANGE.
C       
		 FM = (zmax) / DZ
		 M = IFIX(FM)
		 IF(FM .GT. 0.0)M = M + 1
		 zmp = DZ * FLOAT(M)
C
C       Set levels centered about zero if centered is .true.
C
	         if (centered) then
		    if (abs(znp) .gt. abs(zmp)) then
		       zmp = -znp
		    else
		       znp = -zmp
		    endif
	         endif

C INTEGER based levels
	      else if (intlev.EQ.1) then 

		 znp = FLOOR(zmin)
		 zmp = CEILING(zmax)
C
C       Set levels centered about zero if centered is .true.
C
	         if (centered) then
		    if (abs(znp) .gt. abs(zmp)) then
		       zmp = -znp
		    else
		       znp = -zmp
		    endif
	         endif

	         dz = (zmp - znp)/nlev

		 if (dz.lt.1) then
		     dz = 1
		     i = 1
		     do il = FLOOR(znp),FLOOR(zmp)+1
		        zlev(i) = FLOAT(il)
			i = i+1
		     enddo
		     nlev2 = zmp-znp+2

		  else
		     dz = INT(dz)
		     zz = znp
		     i = 1
		     do while (zz.le. zmp)
		        zlev(i) = zz
			zz = zz + dz
			i = i+1
		     enddo
		     zlev(i) = zz
		     nlev2 = i
		  endif

c       Set THE MINIMUM AND MAXIMUM VALUE OF THE RANGE
		  znp = zlev(1)
		  zmp = zlev(nlev2)

c       Shift the color levels for centered-label key.

		  IF (center_key_labels) CALL SET_LEVELS_CENTERKEY (.TRUE.)

	      else if (openlev) then
	         CALL set_open_levels

C       Else we should allow RANGE to determine the max and min range
C       values and also the appropriate delta value. (ZNP, ZMP, DZ)

	      else

	         znp = zmin
	         zmp = zmax
	         if (centered) then
		    if (abs(znp) .gt. abs(zmp)) then
		       zmp = -znp + zmean
		    else
		       znp = -zmp + zmean
		    endif
	         endif
		 CALL RANGE(znp,zmp,NLEV,ZNP,ZMP,DZ)

	      endif

              IF (.NOT.openlev) THEN

* nlev2 is 1 more than the # of intervals; it is the edges of the intervals, i.e. 
* upper-limit of the uppermost interval minus the lower-limit of the low cell, 
* and then add 1.5 for correct roundoff.

	      NLEV2 = (ZMP-ZNP)/DZ + 1.5

c *acm* 4/08 Set jj as in plotz

              IF (TM_FPEQ_SNGL((ZNP + DZ*(NLEV2-1)), ZMP) .EQV. .FALSE.) THEN
                 IF (ZNP + DZ*(NLEV2-1) .LT. ZMP) NLEV2 = NLEV2 + 1
	      ENDIF

	      IF (ZMP-ZNP .EQ. 0) THEN
                 JJ=NSIGC
              ELSE
                 JJ=NSIGC-IFIX(ALOG10(ABS(ZMP-ZNP))+.5)
              ENDIF
c  Auto-generated integer levels? No need for digits after decimal pt
	      IF (DZ - IFIX(DZ) .EQ. 0.) JJ = 0 
              IF (JJ.LE.0) JJ=-1

c *acm* 3/04 under g77 on linux this incorrectly uses
c            low-order bits to reset NLEV2 example:
c             yes?shade/lev=c {-1.1, 1.1}* ysequence({1,1})

c       4/04  But, dont just skip this, use TM_FPEQ_SNGL to see if
c             values are equal... 
c       4/04  Also fix the negative-range case.

	      IF ( (ZNP + DZ*(NLEV2-1) .LT. ZMP) .AND. 
     .              .NOT. TM_FPEQ_SNGL(ZNP + DZ*(NLEV2-1), ZMP) ) THEN
		 NLEV2 = NLEV2 + 1
	      ENDIF

              IF (NLEV2 .GT. ICNLEV) GO TO 5000

C acm 12/01  Set LWGT for future contour line overlays.

	      DO 100 I=1,NLEV2 

                 LWGT(I)=2
                 LDIG(I)=-1
                 ZLEV(I)=ZNP+DZ*FLOAT(I-1)
                 IF (ABS(ZLEV(I)).LT.1.E-5*DZ) GOTO 100
                 IF (ZLEV(I).GT.0.) THEN
                    LWGT(I)=1
                 ELSE
                    LWGT(I)=3
                 END IF
                 LDIG(I)=JJ


 100	      CONTINUE 

              endif  ! openlev

	   ENDIF

	   
	   IF (center_key_labels) CALL SET_LEVELS_CENTERKEY (.TRUE.)


C       
C       Else IAUTOC != 1 means: use supplied levels
C       

C       
	ELSE  ! iautoc = 0

C	FIND MIN AND MAX as in lev.F from the Z levels.

	   DMIN=ZLEV(1)
	   IF (neginf) DMIN = ZLEV(2)
	   DMAX=DMIN
           DZMAX = 0.
	   DO 110 I=2,NLEV
	      IF(ZLEV(I).GT.DMAX)DMAX=ZLEV(I)
	      IF(ZLEV(I).LT.DMIN)DMIN=ZLEV(I)
              DZ = ZLEV(I)-ZLEV(I-1)
              IF (DZ .GT. DZMAX) DZMAX = DZ
110        CONTINUE

	   znp = dmin
	   zmp = dmax

	   isinf = (neginf .OR. posinf)
	   IF (.NOT.isinf .AND. (DMIN.EQ.DMAX)) THEN
c	      NLEV2=0
	      NLEV2=1
	   ELSE
	   
	   IF (openlev) THEN
	      CALL set_open_levels
	   ELSE
	      NLEV2=NLEV
              IF (neginf) zlev(1) = MIN( zlev(1), zmin-1. )

c       Shift the color levels for centered-label key.

              IF (center_key_labels) THEN
	         CALL SET_LEVELS_CENTERKEY (.TRUE.)
		 nlev = nlev2
	      ENDIF

              IF (posinf .AND. .NOT.center_key_labels) zlev(nlev) = MAX (zlev(nlev), zmax+1. )

	      IF (posinf .AND. neginf .AND. NLEV.EQ.3) THEN
	         nlev = 2
		 nlev2 = 2
	      ENDIF

C Compute the digits in the contour levels, and line characteristics
C these will not have been set before on, say a previous SHADE plot
C 8/07 ACM. Do this computation only for auto-level setting. If the user
C      has set levels, this is already done (and the values are different).

              IF (iautoc .EQ. 1) THEN
                 znp = dmin
                 zmp = dmax
                 dz = 0
                 IF (set_delta) THEN
                    dz = delta
	            IF (ZNP + DZMAX*(NLEV2-1) .LT. ZMP) NLEV2 = NLEV2 + 1
                 ENDIF

	         IF (ZMP-ZNP .EQ. 0) THEN
                    JJ=NSIGC
                 ELSE
                    JJ=NSIGC-IFIX(ALOG10(ABS(ZMP-ZNP))+.5)
                 ENDIF
                 IF (JJ.LE.0) JJ=-1

                 IF (NLEV2 .GT. ICNLEV) GO TO 5000

	         DO 106 I=1,NLEV2
		    LWGT(I)=2
		    LDIG(I)=-1
		    IF (ABS(ZLEV(I)).LT.1.E-5*DZMAX) GOTO 106
                    IF ( TM_FPEQ_SNGL( ABS(ZLEV(I)) ,0.) ) GOTO 106
		    IF (ZLEV(I).GT.0.) THEN
		       LWGT(I)=1
		    ELSE
		       LWGT(I)=3
		    END IF
		    LDIG(I)=JJ
 106	         CONTINUE
   
	      ENDIF
	   ENDIF

        ENDIF  ! openlev
	END IF

! Set ldig: If this is a contour plot, there may have been a 
! PPL CONSET which needs to be applied.

	If (NEWSIG.GT.0) then
	IF (ZMP-ZNP .EQ. 0) THEN
	   JJ=NSIGC
	ELSE
	   JJ=NSIGC-IFIX(ALOG10(ABS(ZMP-ZNP))+.5)
	ENDIF
	IF (JJ.LE.0) JJ=-1

	DO 107 I=1,NLEV2
	   LDIG(I)=-1
	   IF ( TM_FPEQ_SNGL( ABS(ZLEV(I)) ,0.) ) GOTO 107
	   LDIG(I)=JJ
 107	CONTINUE
	endif

* Now that the levels are set, create the LEVELS symbols

        CALL setlab_syms (ZLEV, MAX(NLEV2,1) )

	RETURN
 5000   status = ferr_out_of_range
        RETURN

	END
