




; two instruments to do second order digital filtering
; score data:  p5 = center freq,   p6 = bandwidth  (cps)


	sr = 10000
	kr = 10000
	ksmps = 1
	nchnls = 1

	instr	1
ayt1	init	0
ayt2	init	0

i3	= exp(-6.283185*p6/10000)
i2	= 4*i3*cos(6.283185*p5/10000)/(1+i3)
i1	= (1-i3)*sqrt(1-i2*i2/(4*i3))		;for scale 1

;i4	= (i3+1)
;i1	= sqrt((1-i3)/i4*(i4*i4-i2*i2)		;for scale 2

asig	rand	p4

afilt	= i1*asig + i2*ayt1 - i3*ayt2
ayt2	= ayt1
ayt1	= afilt

aout	linen	afilt, .01, p3, .01
	out	aout
	endin


	instr	2
asig	rand	p4
afilt	reson	asig, p5, p6, 1
aout	linen	afilt, .01, p3, .01
	out	aout
	endin
