Function Shuffle, arr, seed = sed

;+
; NAME:
;	SHUFFLE
; VERSION:
;	3.0
; PURPOSE:
;	Randomizes an array.
; CATEGORY:
;	Array function.
; CALLING SEQUENCE:
;	Result = SHUFFLE( ARR [, SEED = SEED])
; INPUTS:
;    ARR
;	Array, arbitrary type.
; OPTIONAL INPUT PARAMETERS:
;	None.
; KEYWORD PARAMETERS:
;    SEED
;	Randomization seed, optional.
; OUTPUTS:
;	Returns an array with the same values as the original one but in random
;	order.
; OPTIONAL OUTPUT PARAMETERS:
;	None.
; COMMON BLOCKS:
;	None.
; SIDE EFFECTS:
;	None.
; RESTRICTIONS:
;	None.
; PROCEDURE:
;	Straightforward.  Uses the system routine RANDOMU.
; MODIFICATION HISTORY:
;	Created 1-MAY-1995 by Mati Meron.
;-

    on_error, 1
    if n_elements(sed) ne 0 then wsed = sed

    return, arr(sort(randomu(wsed,n_elements(arr))))
end