def euler(f,y0,a,b,h):
	t,y = a,y0
	while t <= b:
		print "%6.3f %6.3f" % (t,y)
		t += h
		y += h * f(t,y)

def newtoncooling(time, temp):
	return -0.07 * (temp - 20)

euler(newtoncooling,100,0,100,10)