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HELP

function f(x) { y = Math.sin(x/4)-2*Math.cos(x/2); return y }
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aX = -20; bX = 30; aY = -2.5; bY = 3.5
Dx = 5; Dy = 1/2
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xx=[-20,-10,10,20,30]; yy=[-2,-1,1,2,3]
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AX=BX=AY=BY=""
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AAX=aX; BBX=bX; AAY=aY; BBY=bY
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