Trait rug::ops::SubFromRound
source · pub trait SubFromRound<Lhs = Self> {
type Round;
type Ordering;
// Required method
fn sub_from_round(&mut self, lhs: Lhs, round: Self::Round) -> Self::Ordering;
}Expand description
Compound subtraction and assignment to the rhs operand with a specified rounding method.
§Examples
use core::cmp::Ordering;
use rug::float::Round;
use rug::ops::{SubAssignRound, SubFromRound};
use rug::Float;
struct F(f64);
impl SubFromRound<f64> for F {
type Round = Round;
type Ordering = Ordering;
fn sub_from_round(&mut self, lhs: f64, round: Round) -> Ordering {
let mut f = Float::with_val(53, lhs);
let dir = f.sub_assign_round(self.0, round);
self.0 = f.to_f64();
dir
}
}
let mut f = F(5.0);
let dir = f.sub_from_round(3.0, Round::Nearest);
// 3.0 - 5.0 = -2.0
assert_eq!(f.0, -2.0);
assert_eq!(dir, Ordering::Equal);Required Associated Types§
Required Methods§
sourcefn sub_from_round(&mut self, lhs: Lhs, round: Self::Round) -> Self::Ordering
fn sub_from_round(&mut self, lhs: Lhs, round: Self::Round) -> Self::Ordering
Performs the subtraction.
§Examples
use core::cmp::Ordering;
use rug::float::Round;
use rug::ops::SubFromRound;
use rug::Float;
// only four significant bits
let mut f = Float::with_val(4, 0.3);
let dir = f.sub_from_round(-3, Round::Nearest);
// -3.3 rounded up to -3.25
assert_eq!(f, -3.25);
assert_eq!(dir, Ordering::Greater);