proposal: math/big: add functions for floor and ceil of a rational number #76821
Description
Proposal Details
Some computations require floor and ceiling of a rational number.
I propose adding Floor and Ceil methods to big.Rat, which return
the floor and ceiling as a *big.Int respectively.
Pull request #76820
An example use case is computing the Engel expansion:
func toEngel(u *big.Rat) (seq []*big.Int) {
for {
a := new(big.Rat).Inv(u).Ceil()
seq = append(seq, a)
u.Mul(u, new(big.Rat).SetInt(a))
u.Sub(u, big.NewRat(1, 1))
if u.Num().Cmp(big.NewInt(0)) == 0 {
break
}
}
return seq
}