function where_arr, full_arr, sub_arr, count, notequal=notequal, map_ss=map_ss
;
;+
;NAME:
;	where_arr
;PURPOSE:
;	Return the subscripts where a given set of values equal the values
;	in the input array.  It is basically an expansion of IDL where in
;	which the condition to match can be an array.
;CALLING SEQUENCE:
;	ss = where(full_arr, sub_arr)
;	ss = where(a, b)
;	ss = where(a, b, count)
;       ss = where(a, b, count, /notequal) - invert sense
;	ss = where(a, b, count, /map_ss)
;INPUT:
;	full_arr- The complete array which is to be searched
;	sub_arr	- The subset array of the values to search "full_arr" of
;
;KEYWORD PARAMETERS:
;	notequal - if set, return indices where values are NOTEQUAL
;	map_ss	- If set, then return the index in the "sub_arr" where
;		  first occurance of the element exists in the "full_arr"
;		  The length of the output is the same as "full_arr"
;OUTPUT:
;	returns the subscripts where "sub_arr" occurrs in "full_arr".  If
;	there are no matches, return a -1.
;OPTIONAL OUTPUT:
;	count	- The number of matches
;HISTORY:
;	Written 30-Apr-91 by M.Morrison
;                1-Jul-94 (SLF) - add NOTEQUAL keyword 
;		14-Nov-97 (MDM) - Added /MAP_SS keyword
;               09-Mar-98 (JSN) - change loop from integer to long
;-
;
n = n_elements(full_arr)
nn = n_elements(sub_arr)
;
b = lonarr(n)-1
for i=0l,nn-1 do begin
    ss = where(full_arr eq sub_arr(i), count)
    if (count ne 0) then b(ss) = i	
end
;
if (keyword_set(map_ss)) then out = b $
	else out = where(b ge 0,count)

; slf - NOTEQUAL condition (recursive - remove matches (EQUAL) from all indices
if keyword_set(notequal) then $
   return, rem_elem(indgen(n),where_arr(full_arr,sub_arr),count) else return,out

end