[issue35880] math.sin has no backward error; this isn't documented

[Steven D'Aprano]

Steven D'Aprano <steve+python at pearwood.info> added the comment:

> sin(1<<500) is correctly computed as 0.42925739234242827

py> math.sin(1<<500)
0.9996230490249484

Wolfram Alpha says it is 0.429257392342428277735329299112473759079115476327819897...

https://www.wolframalpha.com/input/?i=sin%282^500%29&assumption=%22TrigRD%22+-%3E+%22R%22


> Some text could be added (which I am happy to produce) that explains what backward error means

You could start by telling us here what you mean by backward error. Are you talking about this?

https://en.wikipedia.org/wiki/Numerical_stability#Stability_in_numerical_linear_algebra

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nosy: +steven.daprano

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