Ex. 1 PDEs "JavaScript Error: IPython is not defined" fix

[ahhodson]

Leaving this here in the hopes of saving people who run into the same problem some time:

I believe the first line of code "%matplotlib notebook" references legacy JS code from jupyter notebook v6. If you are using notebook 7 or higher (or jupyter lab like me), attempting to run some of the graphing code later in the document returns the error in the title.

I believe the fix for this is replacing the first line with "%matplotlib widget", which should work as long as ipyml is installed.

[arshadkamal10]

Thanks for sharing this observation. I agree that using "%matplotlib widget" resolves the error found when using "%matplotlib notebook". This is as long as ipyml is installed.