from math import *
from Tkinter import *
root = Tk()
canv = Canvas(root, width = 1000, height = 1000, bg = "white")
canv.create_line(500,1000,500,0,width=2,arrow=LAST) 
canv.create_line(0,500,1000,500,width=2,arrow=LAST) 
xk=1
yk=1
for x in range(300):
	xn=xk
	yn=yk
	xk=x*10
	yk=(1/x)*30
	canv.create_line(xn, yn+500,xk, yk+500, fill="#476042")   
canv.pack()	
root.mainloop()

Traceback (most recent call last):
  File "example.py", line 15, in <module>
    yk=(1/x)*30
ZeroDivisionError: integer division or modulo by zero

yk=(1/x)*30