Finishes the GPU path to a usable state: run_gpu_sweep vectorizes the
expensive discharge across N single-stage configs via the validated
batch integrator (numpy CPU / cupy GPU, same code). Setup (decode +
build_stage_physics) is a fast python loop; the ODE batch is one call.
- Extracted sim/stage.build_stage_physics so the CPU path (run_stage) and
the GPU batch build IDENTICAL physics (coil model, eddy, saturation,
circuit params) -- no divergence by construction.
- Batch integrator hardened: stiff configs that overflow fixed-step RK4
are marked infeasible (blew_up), feasibility = actually-commutated
(committed), warnings silenced via seterr. Single-pulse + eddy mirrored.
- Analytic sensor trigger (constant-velocity approach) for the batch;
inductive threshold check preserved.
Honesty gate: test_batch_sweep validates GPU-path exit velocities against
the CPU run_coilgun -- 0.0% divergence on the checked configs. Limitation
stated plainly: single stage only (multi-stage stays on the CPU sweep);
cupy on the server GPU (1070 passthrough) is the remaining infra step.
91 tests pass.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
