Widgets are not IPython 3 compatible

[flutefreak7]

I found your IPython tutorials very helpful, but I had to convert them to IPython 3 format to get the notebooks to work.

Here is the guide for converting to IPython 3 style widgets: https://ipython.org/ipython-doc/3/whatsnew/version3_widget_migration.html

For the most part it makes the code look better (css properties are now direct attributes, and button styles can be set with button_style attribute, etc.)

Just thought I'd report the suggestion at the very least. There aren't enough good tutorials like this for the IPython widget system.

[icoz]

import numpy as np
import matplotlib.pyplot as plt

from ipywidgets import *
from IPython.display import display