Implement missing traits/functions

[jD91mZM2]

• [x] Rem
• [ ] UpperHex, LowerHex
• [x] abs
• [ ] asin/acos/atan
• [ ] asinh/acosh/atanh
• [ ] floor/ceil/round/trunc
• [ ] hypot
• [ ] ln/log2/log10
• [ ] not/or/and/xor
• [ ] sin/cos/san
• [ ] sinh/cosh/tanh
• [x] sqrt/cbrt
• [ ] trunc/fract

[mmstick]

Once the Float trait is implemented, I should be able to use this in the calculate crate, and subsequently the calc builtin within the Ion shell.

[hgoldstein]

One problem is that Float requires Copy, which is a bit of an issue as BigInt cannot be Copy'd.

EDIT: In addition I guess you could represent nan and inf manually, but I wonder if it would be better to represent it using an enum instead, i.e.:

enum BigDecimal {
  NaN,
  Inf,
  ...
}

[thargor]

abs was implemented in #34

[aidanhs]

rem is done - #38

[Pzixel]

Sqrt is highly demanded. Any progress on that? I probably could implement babylinian sqrt-ion, but i'm not sure if it's what is wanted.

[akubera]

Ok, sqrt() is implemented in my develop branch. It returns Option<BigDecimal> to handle NaN case of √(negative number). Currently it still uses 100 digits of precision, but there's a new method with_prec() that you can use to trim the digits down to a sane number.

Please check it out and let me know if I overlooked anything. The tests were verified by python's decimal sqrt method.

[Pzixel]

Great work!

Gonna try it tomorrow.

[akubera]

sqrt/cbrt implementation in 0d0e5ffa85ec482 should be "final". If someone can check my work or find a corner-case that returns incorrect value or causes an infinite loop, please let me know.

[PaddiM8]

Any progress on this? This crate seems great, but I really need functions like these.

[calvincramer]

I think sqrt / cbrt should honor the precision set by with_prec(), see todo comment: https://github.com/akubera/bigdecimal-rs/blob/master/src/lib.rs#L411 It was a little confusing, since I did not find any mention of the 100 decimal digit limit in the docs.