;+
; NAME:
;       RANGE
; PURPOSE:
;       Returns a range encompassing all values of an array and a
;       certain percentage of the difference between the minimum and
;       maximum value of the array, which is ideal for plotting
;       purposes
; CALLING SEQUENCE:
;       RANGE, array, pct=pct
; EXAMPLES:
;       plot, x, y, xrange=range(x, pct=5), /xr
; KEYWORDS:
;       array = input array
;       pct   = percentage of difference between minimum and maximum
;       value to extend the range with. If 0 then range is exactly
;       minmax.
; MODIFICATION HISTORY:
;       Before 05/06/2007 Written by Eduard Westra
;       12/12/2007 Return a non-zero range when the input has the same
;       number everywhere
;-
FUNCTION range, array, pct=pct
  IF N_ELEMENTS(pct) NE 1 THEN lpct = 0.d ELSE lpct = pct/100.d
  idx = WHERE(FINITE(array) EQ 1)
  mm = minmax(array[idx])
  d  = (diff(mm) EQ 0 ? mm[0] : mm[1]-mm[0])
  RETURN, lpct*[-d, d] + mm
END