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Quadrature Oscillator

SeanCS

This quadrature oscillator might be useful for digital signal processing, graphics and anywhere you need to produce a sin/cos wave form more efficiently that actually calling the slow sin and cos functions:

https://groups.google.com/forum/#!topic/comp.dsp/GFAzbora6bE

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const as single w=.005*(8*atn(1)) 'w= radians per step (so here 200 steps = 2*Pi radians =360 degrees)
dim as single u=0!,v=1!,k1=tan(w*.5),k2=2*k1/(1 + k1*k1)
for j as ulong =0 to 199
var tmp = u - k1*v
v = v + k2*tmp
u= tmp - k1*v
var i=j mod 800
pset (i,225+200*v),rgb(255,0,255)
pset (i,225+200*u),rgb(0,255,255)
pset (400+100*v,225+100*u),rgb(255,255,255)
next
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