Fix the test data matrix script

[jmackay2]

Solved Problem

The matrix test_data.py script did not work.

Solution

• Add python3 shebang
• Remove std::sqrt and replace with a python sqrt (**0.5)
• Add a float epsilon

Alternatives

We could use a python package that does sqrt if we want to be more verbose, but the square function just before is just using python square, so it is probably not necessary.

Test coverage

• Ran the test_data.py script successfully with the outputs printing correctly