Re: [csswg-drafts] [css-values] Does tan(90deg) return +∞, −∞ or NaN? (#4101)

> I would argue strongly for a solution that supports round-tripping, so that atan(tan(90deg)) returns 90deg

IMO `atan(tan(90deg)) = 90deg` should just be a consequence, not what we want to enforce.

Note that `atan ∘ tan` is not the identity, e.g. `atan(tan(2π))` is not `2π` (given the usual definition of `atan`). The identity is `tan ∘ atan`, so if we want to preserve this in CSS, what we actually need is `tan(atan(+∞)) = +∞`. And since `atan(+∞) = 90deg`, then `tan(90deg) = +∞`

-- 
GitHub Notification of comment by Loirooriol
Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/4101#issuecomment-510968263 using your GitHub account

Received on Friday, 12 July 2019 17:28:25 UTC