> Bignums are arbitrarily more accurate than IEEE floats... Yes, and that's true of all arbitrary-sized types vs fixed-size types. There's a lot of costs that

> Bignums are arbitrarily more accurate than IEEE floats... Yes, and that's true of all arbitrary-sized types vs fixed-size types. There's a lot of costs that come with that choice, like inherent allocations, losing constant time operations, lack of hardware support, etc. You can do exactly the same thing with floating point, for example GNU MPFR and ARPREC. Doing so is broadly faster than rational representations for a lot of common types of computations, and much less prone to size explosions. Still has the issue of incorrectly terminated representations at a given size or precision, but they can also represent things like irrationals far more efficiently. That said, I've very rarely run into situations that couldn't be made to fit in a double or quad where rationals would be better. These types can represent the distances between planets down to the nanometer or micrometer scale without losing precision. If you're dealing with atomic manufacturing on an astronomical scale, it might be worth investing in a new type, but anything short of that is very likely to be a problem requiring domain expertise to evaluate. Floats are perfectly fine as a default. The other advantage of floats is that they allow/require you to think about precision and rounding because they're a core part of the representation. Some people don't like that, but going to rational bignums doesn't free you of that burden.