How Square Roots are Calculated in Quake

This has been sitting in my drafts folder, waiting for me to read the article, learn about it and summarize it here.

I took a quick scan today to make sure I wasn’t biting off more than I could chew when I stuck it in the queue. Unfortunately, I don’t think I understand it better than the linked-to-writer and I’m not interested in spending the time to become so.

Here’s the attention-grabbing part:

My Understanding: This incredible hack estimates the inverse root using Newton’s method of approximation, and starts with a great initial guess.

The trick has to do with how floating point numbers are stored in a computer, something I’ve actually blogged about.

Who said math wasn’t useful!

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