Glossary · Phase 2 · Math, when you need it
Projection
The part of a vector that lies along another direction: its shadow on that line. Projecting data onto a few directions is how PCA shrinks it.
Try it now
Drag b around a. Watch the dot product shrink to 0 at a right angle and turn negative past it.
Learn it properly
Dot product and cosine similarity · The one operation behind similarity search and attention. About 25 minutes.
Other terms from the same lesson
- dot product: Multiply two vectors number by number and add up the results. Big when they point the same way.
Never trained an AI?
Teach a small one to write, right in your browser. It takes about 20 seconds and needs no account.