PRO cross_dogs, ra1, dec1, ra2, dec2, radius, index, multi = multi


; DOGS serve CATS
;
;
; well.... This is actually the previous cross_cats.pro.
; The syntax is the same as cross_cats, but is much slower
; than the current cross_cats for catalogs with more than
; a few thousand sources.  If you have huge catalogs, use
; cross_cats.  Cats are much faster and powerful than dogs.
;



n1 = n_elements(ra1)
n2 = n_elements(ra22)

index = lon64arr(n1)*0-1


; exclude sources in the second set that are not within
; the ra/dec ranges of the first set
Z = where(ra2 LE max(ra1) + 5.0*radius/3600.0d * cos(min(abs(dec1)) * !pi/180.0d) AND $
          ra2 GE min(ra1) - 5.0*radius/3600.0d * cos(min(abs(dec1)) * !pi/180.0d) AND $
          dec2 LE max(dec1) + 5.0*radius/3600.0d AND dec2 GE min(dec1) - 5.0*radius/3600.0d)

IF total(Z) EQ -1 THEN goto,finish


Z = long64(Z)
ra22 = ra2[Z]
dec22 = dec2[Z]

If n_elements(multi) EQ 0 THEN multi = 0

IF multi EQ 1 THEN distance = fltarr(n1)

i = long64(0)
WHILE i LT n1 DO BEGIN
   dra = (ra1[i] - ra22)*cos(dec1[i]*!pi/180.0)
   ddec = (dec1[i] - dec22)
   d = 3600.0 * sqrt(dra^2.0 + ddec^2.0)
   dmin = min(d,ind)
   
   IF dmin LE radius THEN index[i] = ind
   IF multi EQ 1 AND dmin LE radius THEN distance[i] = dmin
   i=i+1
ENDWHILE

;index2 = fix(index)
;IF total(index-index2) EQ 0 THEN index = index2


If multi EQ 1 THEN BEGIN

A = where(index NE -1)
nA = n_elements(A)

i = long(0)
WHILE i LT nA DO BEGIN
   B = where(index[A] EQ index[A[i]])
   IF n_elements(B) GE 2 THEN BEGIN
   dmin = min(distance[A[B]], ind)
   temp = index[A[B[ind]]]
   index[A[B]] = -1
   index[A[B[ind]]] = temp
   ENDIF
   i = i+1
ENDWHILE

ENDIF

A = where(index GE 0)
IF total(A) NE -1 THEN index[A] = Z[index[A]]
; Here can be a source of bug.


IF min(index) LT -1 THEN print, 'trouble'


finish:

END