aura-std shipped Sma, Sub, Exposure, SimBroker but no sum, so the north-star
"combine one signal with another" research move (C10) could not be expressed
from shipped blocks — the cycle-0007 fieldtest had to hand-author a project-local
Add2. This adds the missing combinator(s):
- Add — two-input f64 sum (a + b), the parameterless companion to Sub. Mirrors
sub.rs modulo the operator.
- LinComb { weights } — N-input weighted sum (Σ wᵢ·xᵢ). The weights are the
node's tunable parameters (C8/C12) and fix its arity (weights.len() inputs);
this is the form the north-star "combine A and B *with weights*" reaches for.
LinComb([1,1]) is Add; LinComb([1,-1]) is Sub.
Both withhold output (None) until *all* inputs are present — consistent with Sub,
and causally clean: a cold input leg is never silently folded in as 0.0.
LinComb::new panics on empty weights (build-time param error, like Sma::new).
Both ship because each is independently reached-for: Add for readability symmetry
with Sub, LinComb for the weighted/tunable combination — mirroring the project's
already-shipped choice to keep Sub as a named node beside a general form.
Hand-driven unit tests in the established aura-std style (5 new): Add sum, the
Add == LinComb([1,1]) identity, the N>2 warm-up, and the empty-weights panic.
Verified: cargo test -p aura-std (14 passed), clippy --all-targets -D warnings
clean, RUSTDOCFLAGS="-D warnings" cargo doc -p aura-std --no-deps clean.
closes#11
Brummel
84130c2cab