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use super::*;
pub use std::ops::Div;
fn chain_division(vi: &Vari) {
let adj = vi.adj();
match (vi.a.clone(), vi.b.clone()) {
(Operand::Vari(ptr), Operand::Data(bd)) => {
let avi: &mut Vari = ptr.clone().into();
let avi_adj = avi.adj();
avi.set_adj(avi_adj + adj / bd);
}
(Operand::Data(ad), Operand::Vari(ptr)) => {
let bvi: &mut Vari = ptr.clone().into();
let bvi_val = bvi.val();
let bvi_adj = bvi.adj();
bvi.set_adj(bvi_adj - adj * ad / (bvi_val * bvi_val));
}
(Operand::Vari(ap), Operand::Vari(bp)) => {
let avi: &mut Vari = ap.clone().into();
let avi_val = avi.val();
let avi_adj = avi.adj();
let bvi: &mut Vari = bp.clone().into();
let bvi_val = bvi.val();
let bvi_adj = bvi.adj();
avi.set_adj(avi_adj + adj / bvi_val);
bvi.set_adj(bvi_adj - adj * avi_val / (bvi_val * bvi_val));
}
_ => {}
}
}
binop!(impl Div, div
for Var, Real, |x, y| x / y,
for Real, Var, |x, y| x / y,
for Var, Var, |x, y| x / y,
chain Fn = chain_division);
#[cfg(test)]
mod test {
use super::*;
use core::memory::*;
#[test]
fn mul() {
let mut x: Real = 3.6;
let mut y: Real = 3.0;
let stack = Rc::new(RefCell::new(ChainStack::new()));
let vx = var!(stack, x);
let vy = var!(stack, y);
let mut v = &vx / &vy;
v.grad();
assert_eq!(v.val(), x / y);
assert_eq!(vx.adj(), 1.0 / y);
assert_eq!(vy.adj(), -x / (y * y));
v.set_zero_all_adjoints();
y = 8.9;
v = &vx / &y;
v.grad();
assert_eq!(v.val(), x / y);
assert_eq!(vx.adj(), 1.0 / y);
assert_eq!(vy.adj(), 0.0);
v.set_zero_all_adjoints();
x = 83.1;
v = &x / &vy;
v.grad();
assert_eq!(v.val(), x / vy.val());
assert_eq!(vx.adj(), 0.0);
assert_eq!(vy.adj(), -x / (vy.val() * vy.val()));
}
}