1. Add POD.
2. Add more POD.
3. Add still more POD, this time about the expected inputs and outputs.
4. Make people understand what your magic numbers are. Maybe use constants?
5. While on that topic, add more comments, documenting assumptions.

Other than that, it looks great! :-)

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.