Fix/stability not restrict maximun and minimun

[ishiko732]

I referred to the code of fsrs-rs and found that Stability is constrained by maximum and minimum values: https://github.com/open-spaced-repetition/fsrs-rs/blob/bc5d6024effc84b6743186fbdd23cbdf5bb0ec49/src/model.rs#L148-L151.

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[L-M-Sherlock]

Why stability should be constrained by maximum interval?

[ishiko732]

Why stability should be constrained by maximum interval?

I see that in model.rs of fsrs-rs there is a maximum limit of 36500.0. I am thinking that next_interval uses maximum_interval to limit the maximum number of days. Should stability also use maximum_interval to limit its maximum value? Or is it sufficient to just limit the minimum value?

[L-M-Sherlock]

Let's consider such a case: the maximum_interval is 365 days, and the desired retention is 95%. When the stability is ~700 days, the corresponding interval is 365. If we restrict the stability to 365, the interval will never reach 365.

[ishiko732]

Let's consider such a case: the maximum_interval is 365 days, and the desired retention is 95%. When the stability is ~700 days, the corresponding interval is 365. If we restrict the stability to 365, the interval will never reach 365.

OK, you're right, I hadn't considered that fully before. So, should I set the maximum for stability to 36500.0, or is it enough to just limit the minimum value?

[L-M-Sherlock]

Yes, please do it.

[L-M-Sherlock]

LGTM