SUBROUTINE GDSWIZCB(KGDS,IOPT,NPTS,FILL,XPTS,YPTS,RLON,RLAT,NRET,
& LROT,CROT,SROT)
C$$$ SUBPROGRAM DOCUMENTATION BLOCK
C
C SUBPROGRAM: GDSWIZCB GDS WIZARD FOR ROTATED EQUIDISTANT CYLINDRICAL
C PRGMMR: IREDELL ORG: W/NMC23 DATE: 96-04-10
C
C ABSTRACT: THIS SUBPROGRAM DECODES THE GRIB GRID DESCRIPTION SECTION
C (PASSED IN INTEGER FORM AS DECODED BY SUBPROGRAM W3FI63)
C AND RETURNS ONE OF THE FOLLOWING:
C (IOPT=+1) EARTH COORDINATES OF SELECTED GRID COORDINATES
C (IOPT=-1) GRID COORDINATES OF SELECTED EARTH COORDINATES
C FOR STAGGERED ROTATED EQUIDISTANT CYLINDRICAL PROJECTIONS.
C (SEE UNDER THE DESCRIPTION OF KGDS TO DETERMINE WHETHER
C TO COMPUTE A STAGGERED WIND GRID OR A STAGGERED MASS GRID.)
C IF THE SELECTED COORDINATES ARE MORE THAN ONE GRIDPOINT
C BEYOND THE THE EDGES OF THE GRID DOMAIN, THEN THE RELEVANT
C OUTPUT ELEMENTS ARE SET TO FILL VALUES.
C THE ACTUAL NUMBER OF VALID POINTS COMPUTED IS RETURNED TOO.
C
C PROGRAM HISTORY LOG:
C 96-04-10 IREDELL
C 98-08-19 BALDWIN MODIFY GDSWIZC9 FOR TYPE 203 ETA GRIDS
C 2003-06-11 IREDELL INCREASE PRECISION
C
C USAGE: CALL GDSWIZCB(KGDS,IOPT,NPTS,FILL,XPTS,YPTS,RLON,RLAT,NRET,
C & LROT,CROT,SROT)
C
C INPUT ARGUMENT LIST:
C KGDS - INTEGER (200) GDS PARAMETERS AS DECODED BY W3FI63
C IMPORTANT NOTE: IF THE 9TH BIT (FROM RIGHT) OF KGDS(11)
C (SCANNING MODE FLAG) IS 1, THEN THIS
C THE GRID IS COMPUTED FOR A WIND FIELD;
C OTHERWISE IT IS FOR A MASS FIELD. THUS
C MOD(KGDS(11)/256,2)=0 FOR MASS GRID.
C IOPT - INTEGER OPTION FLAG
C (+1 TO COMPUTE EARTH COORDS OF SELECTED GRID COORDS)
C (-1 TO COMPUTE GRID COORDS OF SELECTED EARTH COORDS)
C NPTS - INTEGER MAXIMUM NUMBER OF COORDINATES
C FILL - REAL FILL VALUE TO SET INVALID OUTPUT DATA
C (MUST BE IMPOSSIBLE VALUE; SUGGESTED VALUE: -9999.)
C XPTS - REAL (NPTS) GRID X POINT COORDINATES IF IOPT>0
C YPTS - REAL (NPTS) GRID Y POINT COORDINATES IF IOPT>0
C RLON - REAL (NPTS) EARTH LONGITUDES IN DEGREES E IF IOPT<0
C (ACCEPTABLE RANGE: -360. TO 360.)
C RLAT - REAL (NPTS) EARTH LATITUDES IN DEGREES N IF IOPT<0
C (ACCEPTABLE RANGE: -90. TO 90.)
C LROT - INTEGER FLAG TO RETURN VECTOR ROTATIONS IF 1
C
C OUTPUT ARGUMENT LIST:
C XPTS - REAL (NPTS) GRID X POINT COORDINATES IF IOPT<0
C YPTS - REAL (NPTS) GRID Y POINT COORDINATES IF IOPT<0
C RLON - REAL (NPTS) EARTH LONGITUDES IN DEGREES E IF IOPT>0
C RLAT - REAL (NPTS) EARTH LATITUDES IN DEGREES N IF IOPT>0
C NRET - INTEGER NUMBER OF VALID POINTS COMPUTED
C CROT - REAL (NPTS) CLOCKWISE VECTOR ROTATION COSINES IF LROT=1
C SROT - REAL (NPTS) CLOCKWISE VECTOR ROTATION SINES IF LROT=1
C (UGRID=CROT*UEARTH-SROT*VEARTH;
C VGRID=SROT*UEARTH+CROT*VEARTH)
C
C ATTRIBUTES:
C LANGUAGE: FORTRAN 77
C
C$$$
INTEGER KGDS(200)
REAL XPTS(NPTS),YPTS(NPTS),RLON(NPTS),RLAT(NPTS)
REAL CROT(NPTS),SROT(NPTS)
INTEGER,PARAMETER:: KD=SELECTED_REAL_KIND(15,45)
REAL(KIND=KD):: RERTH,PI,DPR
REAL(KIND=KD):: RLAT1,RLON1,RLAT0,RLON0
REAL(KIND=KD):: SLAT1,CLAT1,SLAT0,CLAT0
REAL(KIND=KD):: CLON1,SLATR,CLATR,CLONR
REAL(KIND=KD):: RLATR,RLONR,DLATS,DLONS,XPTFC,YPTFC,SLON
REAL(KIND=KD):: SLAT,CLAT,CLON,RLATCR,RLONCR,DMIDS,RLATLR,RLONLR
PARAMETER(RERTH=6.3712E6_KD)
PARAMETER(PI=3.14159265358979_KD,DPR=180._KD/PI)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
IF(KGDS(1).EQ.203) THEN
RLAT1=KGDS(4)*1.E-3_KD
RLON1=KGDS(5)*1.E-3_KD
RLAT0=KGDS(7)*1.E-3_KD
RLON0=KGDS(8)*1.E-3_KD
DLONS=KGDS(9)*1.E-3_KD
DLATS=KGDS(10)*1.E-3_KD
DMIDS=SQRT(DLONS*DLONS+DLATS*DLATS)
IROT=MOD(KGDS(6)/8,2)
IM=KGDS(2)*2-1
JM=KGDS(3)
KSCAN=MOD(KGDS(11)/256,2)
ISCAN=MOD(KGDS(11)/128,2)
JSCAN=MOD(KGDS(11)/64,2)
NSCAN=MOD(KGDS(11)/32,2)
HI=(-1.)**ISCAN
HJ=(-1.)**(1-JSCAN)
SLAT1=SIN(RLAT1/DPR)
CLAT1=COS(RLAT1/DPR)
SLAT0=SIN(RLAT0/DPR)
CLAT0=COS(RLAT0/DPR)
HS0=SIGN(1._KD,MOD(RLON1-RLON0+180+3600,360._KD)-180)
CLON1=COS((RLON1-RLON0)/DPR)
SLATR=CLAT0*SLAT1-SLAT0*CLAT1*CLON1
CLATR=SQRT(1-SLATR**2)
CLONR=(CLAT0*CLAT1*CLON1+SLAT0*SLAT1)/CLATR
RLATLR=DPR*ASIN(max(min(SLATR,1.0_KD),-1.0_KD))
RLATCR=RLATLR+(JM-1)/2.*DLATS
RLONLR=HS0*DPR*ACOS(max(min(CLONR,1.0_KD),-1.0_KD))
RLONCR=RLONLR+(IM-1)/2.*DLONS
c$$$ write(0,*) 'clonr=',clonr,' clatr=',clatr,' clon1=',clon1
c$$$ write(0,*)'hs0=',hs0,' acos(clonr)=',acos(clonr),' dlons=',dlons
c$$$ write(0,*) 'rlonlr=',rlonlr
C DLATS=RLATR/(-(JM-1)/2)
C DLONS=RLONR/(-(IM-1)/2)
IF(KSCAN.EQ.0) THEN
IS1=(JM+1)/2
ELSE
IS1=JM/2
ENDIF
XMIN=0
XMAX=IM+1
IF(IM.EQ.NINT(360/ABS(DLONS))) XMAX=IM+2
YMIN=0
YMAX=JM+1
NRET=0
3033 format('gdswizcb: 203 proj info: rlat1=',F0.3,' rlon1=',F0.3,
& ' rlat0=',F0.3,' rlon0=',F0.3,' dlons=',F0.3,
& ' dlats=',F0.3,' rloncr=',F0.3,' rlatcr=',F0.3)
write(0,3033) rlat1,rlon1,rlat0,rlon0,dlons,dlats,rloncr,rlatcr
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C TRANSLATE GRID COORDINATES TO EARTH COORDINATES
IF(IOPT.EQ.0.OR.IOPT.EQ.1) THEN
C Calculate grid center point in rotated coordinates:
XPTFC=(JM-1)/2. + ( (IM-1)/2. - IS1 )
YPTFC=(JM-1)/2. - ( (IM-1)/2. - IS1 ) + KSCAN
DO N=1,NPTS
XPTF=YPTS(N)+(XPTS(N)-IS1)
YPTF=YPTS(N)-(XPTS(N)-IS1)+KSCAN
IF(XPTF.GE.XMIN.AND.XPTF.LE.XMAX.AND.
& YPTF.GE.YMIN.AND.YPTF.LE.YMAX) THEN
RLONR=RLONLR+(XPTF-1)*DLONS
RLATR=RLATLR+(YPTF-1)*DLATS
C HS=HI*SIGN(1.,XPTF-(IM-1)/2.)
HS=HI*SIGN(1._KD,XPTF-XPTFC+1)
IF(ABS(HS)/=1.) HS=1.
RLONR=(XPTF-XPTFC)*DLONS+RLONCR
RLATR=(YPTF-YPTFC)*DLATS+RLATCR
CLONR=COS(RLONR/DPR)
SLATR=SIN(RLATR/DPR)
CLATR=COS(RLATR/DPR)
SLAT=CLAT0*SLATR+SLAT0*CLATR*CLONR
c$$$ write(0,*) 'hs=',hs,' rlonr=',rlonr,' rlatr=',rlatr
IF(SLAT.LE.-1) THEN
CLAT=0.
CLON=COS(RLON0/DPR)
RLON(N)=0
RLAT(N)=-90
ELSEIF(SLAT.GE.1) THEN
CLAT=0.
CLON=COS(RLON0/DPR)
RLON(N)=0
RLAT(N)=90
ELSE
CLAT=SQRT(1-SLAT**2)
CLON=(CLAT0*CLATR*CLONR-SLAT0*SLATR)/CLAT
CLON=MIN(MAX(CLON,-1._KD),1._KD)
RLON(N)=MOD(RLON0+HS*DPR*ACOS(max(min(1.0_KD,CLON),
& -1.0_KD))+3600,360._KD)
c$$$ IF( (RLON(N)>=RLON1) .neqv. (HS0>0) ) THEN
c$$$ IF(RLON(N)<180.) THEN
c$$$ RLON(N)=RLON(N)-360.
c$$$ ELSE
c$$$ RLON(N)=RLON(N)+360.
c$$$ ENDIF
c$$$ ENDIF
RLAT(N)=DPR*ASIN(MAX(MIN(SLAT,1.0_KD),-1.0_KD))
ENDIF
c$$$ 100 format('N=',I0,' lon=',F0.3,' lat=',F0.3,
c$$$ & ' from x=',F0.3,' y=',F0.3,' slat=',F0.3)
c$$$ write(0,100) n,rlon(n),rlat(n),xptf,yptf,slat
NRET=NRET+1
IF(LROT.EQ.1) THEN
IF(IROT.EQ.1) THEN
IF(CLATR.LE.0) THEN
CROT(N)=-SIGN(1._KD,SLATR*SLAT0)
SROT(N)=0
ELSE
SLON=SIN((RLON(N)-RLON0)/DPR)
CROT(N)=(CLAT0*CLAT+SLAT0*SLAT*CLON)/CLATR
SROT(N)=SLAT0*SLON/CLATR
ENDIF
ELSE
CROT(N)=1
SROT(N)=0
ENDIF
ENDIF
ELSE
RLON(N)=FILL
RLAT(N)=FILL
ENDIF
ENDDO
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C TRANSLATE EARTH COORDINATES TO GRID COORDINATES
ELSEIF(IOPT.EQ.-1) THEN
DO N=1,NPTS
IF(ABS(RLON(N)).LE.360.AND.ABS(RLAT(N)).LE.90) THEN
HS=SIGN(1._KD,MOD(RLON(N)-RLON0+180+3600,360._KD)-180)
CLON=COS((RLON(N)-RLON0)/DPR)
SLAT=SIN(RLAT(N)/DPR)
CLAT=COS(RLAT(N)/DPR)
SLATR=CLAT0*SLAT-SLAT0*CLAT*CLON
IF(SLATR.LE.-1) THEN
CLATR=0.
RLONR=0
RLATR=-90
ELSEIF(SLATR.GE.1) THEN
CLATR=0.
RLONR=0
RLATR=90
ELSE
CLATR=SQRT(1-SLATR**2)
CLONR=(CLAT0*CLAT*CLON+SLAT0*SLAT)/CLATR
CLONR=MIN(MAX(CLONR,-1._KD),1._KD)
RLONR=HS*DPR*ACOS(MAX(MIN(CLONR,1.0_KD),-1.0_KD))
RLATR=DPR*ASIN(MAX(MIN(SLATR,1.0_KD),-1.0_KD))
ENDIF
c$$$ XPTF=(IM+1)/2+RLONR/DLONS
c$$$ YPTF=(JM+1)/2+RLATR/DLATS
c$$$ XPTF=(IM-1)/2.+(RLONR-RLONCR)/DLONS
c$$$ YPTF=(JM-1)/2.+(RLATR-RLATCR)/DLATS
XPTF=(RLONR-RLONLR)/DLONS+1
YPTF=(RLATR-RLATLR)/DLATS+1
c$$$ 200 format('N=',I0,' lon=',F0.3,' lat=',F0.3,
c$$$ & ' becomes x=',F0.3,' y=',F0.3)
c$$$ write(0,200) n,rlon(n),rlat(n),xptf,yptf
IF(XPTF.GE.XMIN.AND.XPTF.LE.XMAX.AND.
& YPTF.GE.YMIN.AND.YPTF.LE.YMAX) THEN
XPTS(N)=IS1+(XPTF-(YPTF-KSCAN))/2
YPTS(N)=(XPTF+(YPTF-KSCAN))/2
NRET=NRET+1
IF(LROT.EQ.1) THEN
IF(IROT.EQ.1) THEN
IF(CLATR.LE.0) THEN
CROT(N)=-SIGN(1._KD,SLATR*SLAT0)
SROT(N)=0
ELSE
SLON=SIN((RLON(N)-RLON0)/DPR)
CROT(N)=(CLAT0*CLAT+SLAT0*SLAT*CLON)/CLATR
SROT(N)=SLAT0*SLON/CLATR
ENDIF
ELSE
CROT(N)=1
SROT(N)=0
ENDIF
ENDIF
ELSE
XPTS(N)=FILL
YPTS(N)=FILL
ENDIF
ELSE
XPTS(N)=FILL
YPTS(N)=FILL
ENDIF
ENDDO
ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C PROJECTION UNRECOGNIZED
ELSE
IRET=-1
IF(IOPT.GE.0) THEN
DO N=1,NPTS
RLON(N)=FILL
RLAT(N)=FILL
ENDDO
ENDIF
IF(IOPT.LE.0) THEN
DO N=1,NPTS
XPTS(N)=FILL
YPTS(N)=FILL
ENDDO
ENDIF
ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
END