Skip to content

Improves FMA mul_add implementation #150

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 5 commits into
base: master
Choose a base branch
from
Open

Improves FMA mul_add implementation #150

Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
46d2036
use auxiliary variables as in documented formula
PaulXiCao Oct 25, 2025
d2481a0
recommended impl from #148
PaulXiCao Oct 25, 2025
d984ef8
update method documentation formula
PaulXiCao Oct 25, 2025
00ac3a2
add trait bound
PaulXiCao Oct 25, 2025
bed1daa
move trait bounds into where clause
PaulXiCao Oct 25, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
22 changes: 16 additions & 6 deletions src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -787,19 +787,29 @@ impl<T: Clone + Num> Mul<Complex<T>> for Complex<T> {
}
}

// (a + i b) * (c + i d) + (e + i f) == ((a*c + e) - b*d) + i (a*d + (b*c + f))
impl<T: Clone + Num + MulAdd<Output = T>> MulAdd<Complex<T>> for Complex<T> {
// (a + i b) * (c + i d) + (e + i f) == (a*c - (b*d - e)) + i (a*d + (b*c + f))
impl<T> MulAdd<Complex<T>> for Complex<T>
where
T: Clone + Num + MulAdd<Output = T> + Neg<Output = T>,
{
type Output = Complex<T>;

#[inline]
fn mul_add(self, other: Complex<T>, add: Complex<T>) -> Complex<T> {
let re = self.re.clone().mul_add(other.re.clone(), add.re)
- (self.im.clone() * other.im.clone()); // FIXME: use mulsub when available in rust
let im = self.re.mul_add(other.im, self.im.mul_add(other.re, add.im));
let (a, b) = (self.re, self.im);
let (c, d) = (other.re, other.im);
let (e, f) = (add.re, add.im);

let re = a
.clone()
.mul_add(c.clone(), -b.clone().mul_add(d.clone(), -e)); // FIXME: use mulsub when available in rust
let im = a.mul_add(d, b.mul_add(c, f));
Complex::new(re, im)
}
}
impl<'a, 'b, T: Clone + Num + MulAdd<Output = T>> MulAdd<&'b Complex<T>> for &'a Complex<T> {
impl<'a, 'b, T: Clone + Num + MulAdd<Output = T> + Neg<Output = T>> MulAdd<&'b Complex<T>>
for &'a Complex<T>
{
type Output = Complex<T>;

#[inline]
Expand Down