ruv 895c04747e perf(wifi-densepose-sar): incremental phasor rotation in backprojection (~4.4-4.5x, MEASURED) ...

focus_at_point called Complex64::from_polar (a sin/cos pair) once per
(pose, frequency) term. FrequencySweep::frequencies() produces evenly
spaced frequencies by construction, so the per-term phase is an
arithmetic progression in the frequency index -- the phasor can be
evaluated once per pose and advanced by a fixed complex-multiply step
per frequency instead, turning K trig evaluations into 2.

focus_at_point's signature changes from a raw &[f64] frequency slice
to &FrequencySweep, so the evenly-spaced-frequencies precondition
this optimization depends on is a type-level invariant rather than a
caller-observed one -- an arbitrary non-uniform frequency list is no
longer constructible through this API at all.

MEASURED (criterion regression detection, p < 0.001): ~4.4-4.5x
faster across 512/4096/32768-voxel grids (300us/1.97ms/14.5ms vs the
prior 1.47ms/10.4ms/73.5ms). Proven equivalent, not just faster: a new
test independently reimplements the direct per-frequency computation
as a reference and checks the optimized path against it across four
sweep sizes (incl. the n_steps=1 degenerate case) and both on-target
and off-target points, to <1e-9 relative error.

25 tests (22 unit + 3 integration), 0 failed, clippy-clean.

2026-07-30 21:09:57 -04:00

..

physics_validation.rs

perf(wifi-densepose-sar): incremental phasor rotation in backprojection (~4.4-4.5x, MEASURED)

2026-07-30 21:09:57 -04:00