function jdate,yymmdd

;This function returns the julian day for an integer input for the
;year (good up to year 2000)
;
;One oddity of this program is that if the input is a scalar, the
;output is a scalar. If the input is a matrix, the output is a matrix.
;At first it would seem that one could write this code with one loop
;making the scalar case a 1x1 matrix - but this wreaks havoc if the
;output is to be used as an index in a matrix.
;
;BWBerger 12/6/98
;
;Modified by BWBerger 6/30/99 to make program y2k compatible.


rw=row(yymmdd)
cl=col(yymmdd)

if rw eq 1 and cl eq 1 then begin

 ymd=strtrim(string(yymmdd),2)
 if (yymmdd le 991231) then begin ;year is 2-digits
    if yymmdd lt 501231 then begin ;year should most likely have be
                                   ;given in 4-digits  
       print,'jdate.pro failure. You must supply 4-digit year for yr>=2000.'
       jday=-999.
       goto,fini ;year is 2000>2050 but only 2-digits given, this is an error
    endif else begin ;year is 2-digit and probably ok
       yr=long(strmid(ymd,0,2))
       mo=long(strmid(ymd,2,2))
       dy=long(strmid(ymd,4,2))
    endelse
 endif else begin ;otherwise year is 4-digits
    yr=long(strmid(ymd,0,4))
    mo=long(strmid(ymd,4,2))
    dy=long(strmid(ymd,6,2))
 endelse

 ; computes integer julian day from yr, mo, dy.
 ; OK with leap years

 case 1 of
  ((mo eq 1)):begin
    jday=0+dy
  end
  ((mo eq 2)):begin
    jday=31+dy
  end
  (((mo eq 3) and (yr/4. ne fix(yr/4.)))):begin
    jday=59+dy
  end
  (((mo eq 3) and (yr/4. eq fix(yr/4.)))):begin
    jday=60+dy
  end
  (((mo eq 4) and (yr/4. ne fix(yr/4.)))):begin
    jday=90+dy
  end
  (((mo eq 4) and (yr/4. eq fix(yr/4.)))):begin
    jday=91+dy
  end
  (((mo eq 5) and (yr/4. ne fix(yr/4.)))):begin
    jday=120+dy
  end
  (((mo eq 5) and (yr/4. eq fix(yr/4.)))):begin
    jday=121+dy
  end
  (((mo eq 6) and (yr/4. ne fix(yr/4.)))):begin
    jday=151+dy
  end
  (((mo eq 6) and (yr/4. eq fix(yr/4.)))):begin
    jday=152+dy
  end
  (((mo eq 7) and (yr/4. ne fix(yr/4.)))):begin
    jday=181+dy
  end
  (((mo eq 7) and (yr/4. eq fix(yr/4.)))):begin
    jday=182+dy
  end
  (((mo eq 8) and (yr/4. ne fix(yr/4.)))):begin
    jday=212+dy
  end
  (((mo eq 8) and (yr/4. eq fix(yr/4.)))):begin
    jday=213+dy
  end
  (((mo eq 9) and (yr/4. ne fix(yr/4.)))):begin
    jday=243+dy
  end
  (((mo eq 9) and (yr/4. eq fix(yr/4.)))):begin
    jday=244+dy
  end
  (((mo eq 10) and (yr/4. ne fix(yr/4.)))):begin
    jday=273+dy
  end
  (((mo eq 10) and (yr/4. eq fix(yr/4.)))):begin
    jday=274+dy
  end
  (((mo eq 11) and (yr/4. ne fix(yr/4.)))):begin
    jday=304+dy
  end
  (((mo eq 11) and (yr/4. eq fix(yr/4.)))):begin
    jday=305+dy
  end
  (((mo eq 12) and (yr/4. ne fix(yr/4.)))):begin
    jday=334+dy
  end
  (((mo eq 12) and (yr/4. eq fix(yr/4.)))):begin
    jday=335+dy
  end
 endcase
endif else begin

 jday=intarr(cl,rw)

 if rw gt cl then begin
    leng=rw
 endif else begin
    leng=cl
 endelse

 for k=0,leng-1 do begin

  ymd=strtrim(string(yymmdd(k)),2)
  if (yymmdd(k) le 991231) then begin ;year is 2-digits
    if yymmdd(k) lt 501231 then begin ;year should most likely have be
                                   ;given in 4-digits  
       print,'jdate.pro failure. You must supply 4-digit year for yr>=2000.'
       jday(k)=-999.
       goto,fini ;year is 2000>2050 but only 2-digits given, this is an error
    endif else begin ;year is 2-digit and probably ok
       yr=long(strmid(ymd,0,2))
       mo=long(strmid(ymd,2,2))
       dy=long(strmid(ymd,4,2))
    endelse
  endif else begin ;otherwise year is 4-digits
    yr=long(strmid(ymd,0,4))
    mo=long(strmid(ymd,4,2))
    dy=long(strmid(ymd,6,2))
  endelse

  ; computes integer julian day from yr, mo, dy.
  ; OK with leap years

  case 1 of
   ((mo eq 1)):begin
    jday(k)=0+dy
   end
   ((mo eq 2)):begin
    jday(k)=31+dy
   end
   (((mo eq 3) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=59+dy
   end
   (((mo eq 3) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=60+dy
   end
   (((mo eq 4) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=90+dy
   end
   (((mo eq 4) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=91+dy
   end
   (((mo eq 5) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=120+dy
   end
   (((mo eq 5) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=121+dy
   end
   (((mo eq 6) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=151+dy
   end
   (((mo eq 6) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=152+dy
   end
   (((mo eq 7) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=181+dy
   end
   (((mo eq 7) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=182+dy
   end
   (((mo eq 8) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=212+dy
   end
   (((mo eq 8) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=213+dy
   end
   (((mo eq 9) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=243+dy
   end
   (((mo eq 9) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=244+dy
   end
   (((mo eq 10) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=273+dy
   end
   (((mo eq 10) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=274+dy
   end
   (((mo eq 11) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=304+dy
   end
   (((mo eq 11) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=305+dy
   end
   (((mo eq 12) and (yr/4. ne fix(yr/4.)))):begin
    jday(k)=334+dy
   end
   (((mo eq 12) and (yr/4. eq fix(yr/4.)))):begin
    jday(k)=335+dy
   end
  endcase
 endfor

endelse

fini:
return,jday
end