From: marcandre-ruby-core@... Date: 2021-07-01T22:53:34+00:00 Subject: [ruby-core:104466] [Ruby master Bug#18018] Float#floor / truncate sometimes result that is too small. Issue #18018 has been reported by marcandre (Marc-Andre Lafortune). ---------------------------------------- Bug #18018: Float#floor / truncate sometimes result that is too small. https://bugs.ruby-lang.org/issues/18018 * Author: marcandre (Marc-Andre Lafortune) * Status: Open * Priority: Normal * Target version: 3.1 * Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN ---------------------------------------- ```ruby 291.4.floor(1) # => 291.4 (ok) 291.4.floor(2) # => 291.39 (not ok) 291.4.floor(3) # => 291.4 (ok) 291.4.floor(4) # => 291.4 (ok) 291.4.floor(5) # => 291.39999 (not ok) 291.4.floor(6) # => 291.4 (ok) ``` `g = f.floor(n)`, for `n > 0` must return the highest float that has the correct properties: * `g` <= `f` * `g`'s decimal string representation has at most `n` digits I'll note that `floor` should be stable, i.e. `f.floor(n).floor(n) == f.floor(n)` for all `f` and `n`. Same idea for `truncate`, except for negative numbers (where `(-f).truncate(n) == -(f.floor(n))` for positive `f`). Noticed by Eust�quio Rangel but posted on the mailing list. Please do not reply that I need to learn how floats work. Note that example given in doc `(0.3/0.1).floor == 2` is not this issue, since `0.3/0.1 #=> 2.9999999999999996` -- https://bugs.ruby-lang.org/ Unsubscribe: