NAME:
	lhr_us
 PURPOSE:
       This routine calculates and returns (2d array) the likelyhood ratio 
	for a set of identifications using a method similar to Wolstencroft et 
	Al. 1986 with the product Q1*Q2 replaced by Q=1
	It also calculates individual reliabilities according to the 
	Sutherland & Saunders (1992) method and returns this and other
	vectors on demand
	It then goes onto produce various histograms (except if noplot set)
 CALLING SEQUENCE:
	result=lhr_us(xmmdb,wfcdb[,dmax,radec_err=radec_err,$
	radec_fromdb=radec_fromdb,rel=rel,]top=top,bot=bot,dr=dr,field=field,$
	magmax=magmax,noplot=noplot,one_per_page=one_per_page)
 INPUTS:
	xmmdb: xmm database 
	wfcdb: wfc dbatabase for extracting magnitudes of candidates
 OPTIONAL INPUT PARAMETERS:
	dmax: max. offset for nearest matches
	radec_err: no (an error to be assigned to every xmm position)
	radec_fromdb: if set, position error extracted for each object from
		xmmdb
	magmax: if set to a magnitude value, then only objects with mag > max
		are included. This can only be used if wfcdb has an item
		labelled 'mag'
 OPTIONAL OUTPUT PARAMETERS:
	rel: if set to a named variable, gets filled with 2d array of 
		individual reliability (lhr/(1+lhr)) values
	rss: if set to a named variable, gets filled with 2d array of 
		individual reliability (S&S) values
	rrut: if set to a named variable, gets filled with 2d array of 
		individual reliability (Rutledge et al) values
		last element has p(no-id)
	top: if set to a named variable, gets filled with 2d array of 
		numerator of lhr values
	bot: if set to a named variable, gets filled with 2d array of 
		denominator of lhr values
	dr: if set to a named variable, gets filled with 2d array of offsets
	noplot: if set, no histogram plots are produced
	one_per_page: if set as well as ps, only one plot per page
 RESTRICTIONS:
	UNTESTED
 CALLED PROCEDURES:
	
 MODIFICATION HISTORY:
	Original by Ignas Snellen
	08-Dec-2000  S. Aigrain: adapted as a separate function
        16-Jan-2001  S. Aigrain: this method separately
	18-Feb-2001  S. Aigrain: Rutledge et al. reliability included, one
		more page of plots.

(See /home/xmmssc/soft/idl/pro/lhr/lhr_us.pro)