An LLM is learning to fill a giant next-token matrix, stored sparsely as training data

iamtrask · x · 2026-11-12

Andrew Trask offers a clean mental model: imagine a matrix whose rows are every possible token combination in a million-token context and whose columns are next-token frequency distributions — that's what an LLM learns to fill. We never fully render it because that wastes space; it's stored in sparse form, which is the token training data itself.

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