objref v1, v2, v3, v4 
objref box, g1, g2, g3, g4, b1   
                
proc setup_gui() {
        box = new VBox()
        box.intercept(1)
        xpanel("")
                xvalue("delay (points)", "delay", 1, "p()")
                xvalue("duration (points)", "duration", 1, "p()")
        xpanel()
        g1 = new Graph()
        b1 = new HBox()
        b1.intercept(1)
        g2 = new Graph()
        g3 = new Graph() 
        b1.intercept(0)
        b1.map()
        g4 = new Graph()
        box.intercept(0)
        box.map()
        g1.size(0,N, -1, 1)  
        g2.size(0,N/2, -1, 1) 
        g3.size(0,N/2, -1, 1)   
        g4.size(0,N, -1, 1)
} 
//@code...
N=128
delay = 0
duration = N/2
setup_gui()
proc p() {
        v1 = new Vector(N)
        v1.fill(1, delay, delay+duration-1)
        v1.plot(g1)
                
        v2 = new Vector()
        v3 = new Vector()
        FFT(1, v1, v2, v3)
        v2.plot(g2)
        v3.plot(g3)
                
        v4 = new Vector()
        FFT(-1, v4, v2, v3)
        v4.plot(g4)
}
p()