Download files related to linking to Python from Excel are to be found in:

Python matrix functions in Excel, using Pyxll:
Download file: http://interactiveds.com.au/software/Matrixpyxll.zip

Python for VBA users – 4; Python data types:  The main Python data types, including numpy arrays, with examples of their use in PyXll functions.
Download file: http://interactiveds.com.au/software/pyTypes.zip

Python for VBA users – 5; Using built in numpy functions:
Download file: http://interactiveds.com.au/software/py_Polynomial.zip

Also see the PyXll add-in, which is required for the downloads in this category.