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pub type Number = f32;
pub type Poly = Vec<Number>;
#[derive(Debug)]
pub enum Lerp {
Node(Box<Lerp>, Box<Lerp>),
Leaf(Number, Number)
}
impl Lerp {
pub fn new(v: Vec<Number>) -> Box<Lerp> {
Lerp::new_s(&v[..])
}
fn new_s(v: &[Number]) -> Box<Lerp> {
match v.len() {
0 => Box::new(Lerp::Leaf(0.0, 0.0)),
1 => Box::new(Lerp::Leaf(v[0], v[0])),
2 => Box::new(Lerp::Leaf(v[0], v[1])),
_ => Box::new(Lerp::Node(Lerp::new_s(&v[0..v.len() - 1]), Lerp::new_s(&v[1..v.len()])))
}
}
}
pub fn lp(l: Box<Lerp>) -> Poly {
match *l {
Lerp::Leaf(a, b) => vec![a, b - a],
Lerp::Node(a, b) => {
let a = lp(a);
let b = lp(b);
let c = poly_sub(&b, &a);
skewed_sum(a, c)
}
}
}
fn poly_sub(a: &Poly, b: &Poly) -> Poly {
let mut r = a.clone();
for i in 0..r.len() {
r[i] -= b[i];
}
r
}
fn skewed_sum(a: Poly, b: Poly) -> Poly {
let mut r = a.clone();
for i in 0..r.len() - 1 {
r[i + 1] += b[i];
}
r.push(b[b.len() - 1]);
r
}
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