環 ( crate::algebra::ring::Ring ) に std::ops::Div を加えて要請したもの.
crate::algebra::ring::Ring
std::ops::Div
/// Algebra - Field ((+, 0), (*, 1), /) use crate::algebra::ring::*; pub trait Field: Ring + std::ops::Div {} impl Field for i64 {} impl Field for f64 {}