Collision probability computation for conjunction assessment
ocaml-merkle-sync: generic Merkle DAG sync; irmin Sync.S module type
ocaml-merkle-sync: reusable sync primitives for any content-addressed DAG.
- Layer 1: anti-entropy gossip (branch head exchange, O(log n))
- Layer 2: merkle descent (DAG diff by hash, dependency-order transfer)
- Bloom filter (FNV-1a, ~1% FP rate)
15 tests passing. Fuzz harness for bloom properties.
irmin/lib/sync.ml: Sync.S module type — discover/locate/fetch/push.
Each backend provides its own implementation.
Also: dune fmt across affected packages.
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test/interop/gmat/test.ml
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test/interop/gmat/test.ml
···
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Alcotest.(check bool) "min distance found" true (Float.is_finite !min_dist);
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Alcotest.(check bool) "min distance < 1000 km" true (!min_dist < 1000.0);
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Alcotest.(check bool) "no collision (> 1 km)" true (!min_dist > 1.0);
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Fmt.pr " Step-based closest approach: %.3f km at %s\n" !min_dist
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!min_epoch
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Fmt.pr " Step-based closest approach: %.3f km at %s\n" !min_dist !min_epoch
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let relative_velocity () =
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let oem1 = parse_oem "conjunction_sat1.oem" in
···
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match Collision.tca ~times ~pos1 ~pos2 ~vel1 ~vel2 with
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| None -> Alcotest.fail "tca returned None"
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| Some tca ->
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Fmt.pr " Step-based TCA: t=%.3f, d=%.3f km\n" !step_min_t
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!step_min_d;
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Fmt.pr " Refined TCA: t=%.3f, d=%.3f km, vrel=%.3f km/s\n"
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tca.time tca.miss_distance tca.relative_velocity;
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Fmt.pr " Step-based TCA: t=%.3f, d=%.3f km\n" !step_min_t !step_min_d;
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Fmt.pr " Refined TCA: t=%.3f, d=%.3f km, vrel=%.3f km/s\n" tca.time
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tca.miss_distance tca.relative_velocity;
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(* Refined miss distance should be <= step-based (quadratic finds the
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true minimum between steps) *)
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Alcotest.(check bool)
···
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done;
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Fmt.pr " Miss distance: %.3f km\n" !min_dist;
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Fmt.pr " Pc: CANNOT COMPUTE — no covariance in OEM\n";
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Fmt.pr
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" GAP: Need GMAT covariance propagation (Propagate ... Covariance)\n";
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Fmt.pr
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" or CDM with covariance to test ocaml-collision Pc computation.\n";
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Fmt.pr " GAP: Need GMAT covariance propagation (Propagate ... Covariance)\n";
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Fmt.pr " or CDM with covariance to test ocaml-collision Pc computation.\n";
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(* This test passes but documents the gap. The real test would be:
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1. Generate GMAT OEM WITH covariance
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2. Construct a CDM from the GMAT data