Contribute is_power_of_ten? #14

Activity

1. cuviper commented on Nov 14, 2018

   

   cuviper

   on Nov 14, 2018

   Member

   More actions

   I'm open to it, if we can present it in a generic trait befitting the rest of the crate. That doesn't mean that you have to have a generic implementation, just that it's designed such that things like BigUint can implement it too. Take the Roots trait, for example.

   The unsigned primitive integers already have is_power_of_two, and a related next_power_of_two. It would be good to also abstract this in a trait, while we're doing it for 10. Something like:

   pub trait Power2: Integer {
       fn is_power_of_two(&self) -> bool;
       fn next_power_of_two(&self) -> Self;
   }
   pub trait Power10: Integer {
       fn is_power_of_ten(&self) -> bool;
       fn next_power_of_ten(&self) -> Self;
   }

   Or maybe just combine those into a single trait Powers. And feel free to suggest a better name.

   Could we reasonably implement checks for arbitrary powers of n? It wouldn't have to be as fast, but I'm wondering if that's feasible and useful to have too.

   👍React with 👍1Reacted by Marcin Mateusz Hanc
2. cuviper commented on Nov 14, 2018

   

   cuviper

   on Nov 14, 2018

   Member

   More actions

   Floored log2 and log10 might also fit into the scope of this design.
3. mohrezaei commented on Nov 14, 2018

   

   mohrezaei

   on Nov 14, 2018

   Last edited by mohrezaei

   Author

   More actions

   A separate trait is consistent with the way I was thinking about it.

   Curious, why don't signed primitive integers implement is_power_of_two? (obviously, all negative numbers would return false).

   How would we abstract over arbitrary powers on n? Extra parameter to the method? I think 2 and 10 are sufficiently interesting to have their own trait.
4. cuviper commented on Nov 14, 2018

   

   cuviper

   on Nov 14, 2018

   Member

   More actions

   Curious, why don't signed primitive integers implement is_power_of_two? (obviously, all negative numbers would return false).

   I'm not sure, but probably just because negative inputs are useless if they're all false.

   Similarly, what would next_power_of_two do with a negative -- jump all the way to 1?

   How would we abstract over arbitrary powers on n? Extra parameter to the method?

   Yeah, fn is_power_of_n(&self, n: u32) -> bool, or maybe n: usize or n: &Self. I'm not sure if this is really useful anywhere, just musing.
5. mohrezaei commented on Nov 14, 2018

   

   mohrezaei

   on Nov 14, 2018

   Author

   More actions

   Alright, that gives me enough to move this over to a PR. Expect something in the next few days. 😄

   👍React with 👍1Reacted by Josh Stone