https://krtffl.dev/tags/streaming/ Recent content in streaming on krtffl.dev Hugo -- gohugo.io en © [krtffl](https://krtffl.dev) Mon, 13 Apr 2026 00:00:00 +0000 https://krtffl.dev/posts/welford-online-variance-rust/ Mon, 13 Apr 2026 00:00:00 +0000 https://krtffl.dev/posts/welford-online-variance-rust/ <p>you want to know if the error rate just spiked. that&rsquo;s a z-score: how many standard deviations is <em>right now</em> away from what <em>normal</em> looked like. simple formula, <code>(x - mean) / stddev</code>, you learned it before you could legally drink.</p> <p>except a standard deviation needs a mean, and a mean needs all the numbers, and the numbers are a log file the size of a small moon. so where, exactly, are you keeping them?</p>