define hwid 25
	set x=1,512
	set y=x*0
	set w=-1**x
	define N 512
	set x=1,$N
	do i=1,10 {
		set t=random($N)-0.5
		set y=y+t
	}
	set y=y/10
!	window 1 2 1 2
	limits x y
	box
!	connect x y


	window 1 3 1 3
	set z=x*0
	set y=y*w
	fft 1 y z r i
	set r=r*w
	set i=i*w
	set xt=x-257
	set xx=xt concat xt
	set yy=r concat i
	limits xx yy
!	limits -10 10 yy
	box
	connect xt r
	ctype red
	connect xt i
	ctype default

	define hwid 5
 	set f=x>(57-$hwid) && x <  (57+$hwid) ? 1 : 0
 	set f2=x>(457-$hwid) && x <  (457+$hwid) ? 1 : 0
	set f=f+f2
	set r=r*f
	set i=i*f

	window 1 3 1 2
	box
	connect xt r
	ctype red
	connect xt i
	ctype default

	set r=r*w
	set i=i*w
	fft -1 r i y z
	set y=y*w
	window 1 3 1 1
	limits x y
	connect x y