f = lambda x: x * x * x - 3 * x * x + 2 * x

step = 0.001 
start = -1
stop = 3

sign = f(start) > 0

x = start
while x <= stop:
    value = f(x)

    if value == 0:
        
        print , x
    elif (value > 0) != sign:
        
        print , x

    
    sign = value > 0

    x += step