; IDL Version 3.1.0 (RISC/os mipseb)
; Journal File for steele@jasper
; Working directory: /wesson/user/steele/idl
; Date: Tue Feb  1 13:20:35 1994
 
n=1024
t=0.5
x=FINDGEN(n)*t
n21=n/2+1
f=INDGEN(n)
f(n21)=n21-n+FINDGEN(n21-2)
f=f/(n*t)

y1=COS(2.*!PI*x*0.1)
f1=FFT(y1,-1)

!P.MULTI=[0,0,4,0,0]
WINDOW,0,XSIZE=640,YSIZE=960

PLOT,x,y1
PLOT,SHIFT(f,-n21),SHIFT(FLOAT(f1),-n21),YTIT='Real Part',TIT='FFT'
PLOT,SHIFT(f,-n21),SHIFT(IMAGINARY(f1),-n21),YTIT='Imaginary Part',TIT='FFT'
PLOT_IO,SHIFT(f,-n21),SHIFT(ABS(f1),-n21),YTIT='Modulus',TIT='FFT'
END