C+
C NAME:
C	nrLocate
C PURPOSE:
C	Find the position of X in an array XX
C CATEGORY:
C	Math: table searching
C CALLING SEQUENCE:
	subroutine nrLocate(N,XX,X,J)
C INPUTS:
C	N	integer		dimension of array XX
C	XX	real		array; MUST be monotonic
C	X	real		value for which position in XX is required
C OUTPUTS:
C	J	integer		index of array XX such that X lies between
C				XX(J) and XX(J+1)
C				- if X < X(1) then J=0
C				- if X > X(N) then X=N
C RESTRICTIONS:
C	The array XX must be monotonic (increasing or decreasing).
C	NO CHECK IS MADE TO ENSURE THIS IS THE CASE.
C PROCEDURE:
C	See Numerical Recipes, par. 3.4, p. 90
C	Uses standard bisection procedure.
C	See href=nrHunt= if a good initial guess is available
C MODIFICATION HISTORY:
C	JUN-1993, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
C-
	    integer	N
	    real	XX(N)
	    real	X
	    integer	J

	JL = 0
	JU = N+1

	do while (JU-JL .gt. 1)
	    JM = (JU+JL)/2
	    if ( (XX(N) .gt. XX(1)) .eqv. (X .gt. XX(JM)) ) then
		JL = JM
	    else
		JU = JM
	    end if
	end do
	J = JL

	return
	end