Tested Q_rsqrt on Apple M4 (Mac mini) and Zen 3 (Ryzen 5800HS / WSL2). M4's -O2 already rewrites 1/sqrtf to frsqrte and ties Q_rsqrt; x86 clang needs -ffast-math or hits a 12x gap. Hand-written NEON/SSE wrappers turn out slower. Newton 0/1/2 error and the Lomont constant covered too.
Tested BMBrick's LEGO mosaic pipeline in Node + sharp with a 45-color palette: RGB nearest sprinkles 16% glitter and silver on photos, OKLab + material penalty wipes them out, and the original 0.15 is 7× overkill (0.02 is already enough).
A browser tool that reads MusicXML and returns fingerings tuned to your hand size and biomechanical constraints. Walks through the backtracking cost minimization, the actual weight values, the academic lineage since Parncutt 1997, and why the same framework generalizes to guitar.
