;+

;PROCEDURE:	rerange

;

;PURPOSE:	Reformats arrays so they may be plotted as

;		lattitude and longitude.  Changes arrays so

;		that they are in the intervals [-pi/2, +pi/2]

;		and [-pi, +pi]. Can change both lattitude and 

;		longitude or just longitude.

;

;ARGUMENTS:	lng	The longitude array in radians.

;		lat	The corresponding lattitude array in

;			radians. (Optional)

;KEYWORDS:	degrees	Set this to return the arrays in degrees.

;

;Created by:	J.Rauchleiba	12/20/96

;-

pro rerange, lng, lat, degrees=deg



if keyword_set(lat) then begin

	if n_elements(lng) NE n_elements(lat) then $

		message, 'LNG and LAT arrays must be equal length.'



	lat = lat MOD (2*!pi)

	under = where(lat LT -!pi/2, count)

	if count GT 0 then begin

		lat(under) = -lat(under) - !pi

		lng(under) = lng(under) - !pi

	endif



	over = where(lat GT !pi/2, count)

	if count GT 0 then begin

		lat(over) = -lat(over) + !pi

		lng(over) = lng(over) - !pi

	endif

endif



lng = lng MOD (2*!pi)

under = where(lng LT -!pi, count)

if count GT 0 then lng(under) = lng(under) + 2*!pi



over = where(lng GT !pi, count)

if count GT 0 then lng(over) = lng(over) - 2*!pi



if keyword_set(deg) then begin

	if keyword_set(lat) then lat = lat*!radeg

	lng = lng*!radeg

endif



return

end