import math._
def f(x:Double):Double={
    // 3*x*x+x  // or 3*math.pow(3,2)+x
    sin(x)
}
clear
val (s, e, step)= (-10.0, 10.0, 0.1)
val (sx, sy) = (10, 100)
val (tx, ty) = (newTurtle, newTurtle)
runInBackground {
    tx.jumpTo(s*sx,0) ; tx.moveTo(e*sx,0)
}
runInBackground {
    ty.jumpTo(0,-1*sy)
    ty.moveTo(0,sy*(s to e by step).map(f).max)
}
jumpTo(s*sx,f(s)*sy)
for(x <- s to e by step)
    moveTo(x*sx,f(x)*sy)