Comparison
DeterministicvsNon-determinism
Deterministic
you run it twice with the same input and get byte-identical output, because nothing inside it reads the clock or a random number.
The property that the same inputs always produce the same output. It is about reproducibility, not about repeat-safety: a deterministic function can still be unsafe to run twice if it has side effects, and an idempotent operation can be non-deterministic in what it returns. Determinism is what makes replay, caching and testing possible.
Full entry →Non-determinism
you sent the same prompt twice and got two different answers, and nothing in your code changed between the calls.
The same input yielding different outputs run to run, due to sampling and infrastructure. Consequences: evals need multiple runs or temperature 0 to be stable, and 'it worked when I tried it' is not evidence. Design tests and retries with this as a baseline fact.
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