;	(4-apr-91)
FUNCTION CC_FFT,A,B
;+
; NAME:
;	CC_FFT
;	
; PURPOSE:
;	Calculate the cross correlation of two arrays using FFT's
;
; CALLING SEQUENCE:
;	CC = CC_FFT(A,B)
;
; INPUTS:
;	A,B = Square arrays of any type, to be cross correlated
;
; OUTPUTS:
;	CC = Cross correlation array of A and B
;
; MODIFICATION HISTORY:
;	Version 1.0 - Apr, 1991, G. L. Slater, LPARL
;-

siza = size(a) & sizb = size(b)
xdima = siza(1) & ydima = siza(2) & xdimb = sizb(1) & ydimb = sizb(2)
if (xdima ne ydima) or (xdima ne xdimb) or (ydima ne ydimb) then begin
  print, $
    ' ERROR IN CC_FFT: ARRAYS MUST BE SQUARE, OF SAME TYPE AND LENGTH.'
  stop
endif

return, fft(fft(a,-1)*conj(fft(b,-1)),1)
end