Ryan Malloy
70420c3b4f
Add Universal Variable Lambert solver for computing transfer orbits between any two planets. Enables pork chop plot generation as SQL: SELECT dep_date, arr_date, lambert_c3(3, 4, dep_date, arr_date) FROM generate_series(...) dep CROSS JOIN generate_series(...) arr; New functions: - lambert_transfer(dep_body, arr_body, dep_time, arr_time) → RECORD Returns C3 departure/arrival (km^2/s^2), v_infinity (km/s), time of flight (days), and transfer orbit SMA (AU). - lambert_c3(dep_body, arr_body, dep_time, arr_time) → float8 Convenience: departure C3 only, NULL on solver failure. The solver uses Stumpff functions for unified elliptic/parabolic/hyperbolic handling, with Newton-Raphson iteration and bisection fallback. Each solve is sub-millisecond; PARALLEL SAFE for batch computation. All 11 regression tests pass.
102 lines
4.6 KiB
SQL
102 lines
4.6 KiB
SQL
-- lambert_transfer regression tests
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--
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-- Tests interplanetary Lambert transfer orbit solver.
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-- Reference: Hohmann Earth-Mars transfer ~8.5 months, C3 ~8-16 km^2/s^2.
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-- ============================================================
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-- Test 1: Earth-Mars Hohmann-like transfer (2026 window)
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-- Typical Earth-Mars C3 departure: 8-20 km^2/s^2
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-- Transfer time: ~200-300 days
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-- ============================================================
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SELECT 'earth_mars_transfer' AS test,
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round(c3_departure::numeric, 1) AS c3_dep,
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round(c3_arrival::numeric, 1) AS c3_arr,
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round(v_inf_departure::numeric, 1) AS vinf_dep,
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round(v_inf_arrival::numeric, 1) AS vinf_arr,
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round(tof_days::numeric, 0) AS tof,
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round(transfer_sma::numeric, 2) AS sma_au
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FROM lambert_transfer(3, 4,
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'2026-05-01 00:00:00+00'::timestamptz,
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'2027-01-15 00:00:00+00'::timestamptz);
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-- ============================================================
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-- Test 2: Earth-Venus transfer
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-- Venus is closer, so C3 should be lower (~5-15 km^2/s^2).
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-- Transfer time: ~100-200 days typical.
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-- ============================================================
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SELECT 'earth_venus_transfer' AS test,
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round(c3_departure::numeric, 1) AS c3_dep,
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round(tof_days::numeric, 0) AS tof,
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round(transfer_sma::numeric, 2) AS sma_au
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FROM lambert_transfer(3, 2,
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'2026-06-01 00:00:00+00'::timestamptz,
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'2026-10-15 00:00:00+00'::timestamptz);
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-- ============================================================
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-- Test 3: lambert_c3 convenience function
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-- Should match c3_departure from lambert_transfer.
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-- ============================================================
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SELECT 'c3_convenience' AS test,
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round(lambert_c3(3, 4,
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'2026-05-01 00:00:00+00'::timestamptz,
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'2027-01-15 00:00:00+00'::timestamptz)::numeric, 1) AS c3;
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-- ============================================================
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-- Test 4: Earth-Jupiter transfer (longer, higher energy)
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-- C3 departure typically 70-100+ km^2/s^2 for direct transfers.
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-- ============================================================
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SELECT 'earth_jupiter_transfer' AS test,
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round(c3_departure::numeric, 0) AS c3_dep,
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round(tof_days::numeric, 0) AS tof
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FROM lambert_transfer(3, 5,
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'2026-01-01 00:00:00+00'::timestamptz,
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'2028-06-01 00:00:00+00'::timestamptz);
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-- ============================================================
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-- Test 5: C3 is in reasonable physical range
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-- Any Earth-Mars transfer should have C3 > 0 and < 200.
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-- ============================================================
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SELECT 'c3_range_check' AS test,
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lambert_c3(3, 4,
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'2026-05-01 00:00:00+00'::timestamptz,
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'2027-01-15 00:00:00+00'::timestamptz) > 0 AS positive,
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lambert_c3(3, 4,
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'2026-05-01 00:00:00+00'::timestamptz,
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'2027-01-15 00:00:00+00'::timestamptz) < 200 AS reasonable;
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-- ============================================================
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-- Test 6: SMA should be between Earth and Mars orbits
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-- Hohmann transfer SMA ~ 1.26 AU for Earth-Mars.
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-- Realistic transfers range ~1.1-2.5 AU.
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-- ============================================================
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SELECT 'sma_range_check' AS test,
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transfer_sma > 0.8 AS above_venus,
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transfer_sma < 5.0 AS below_jupiter
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FROM lambert_transfer(3, 4,
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'2026-05-01 00:00:00+00'::timestamptz,
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'2027-01-15 00:00:00+00'::timestamptz);
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-- ============================================================
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-- Test 7: Error - same body departure and arrival
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-- ============================================================
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SELECT 'same_body_error' AS test, lambert_c3(3, 3, now(), now() + interval '100 days');
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-- ============================================================
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-- Test 8: Error - arrival before departure
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-- ============================================================
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SELECT 'time_error' AS test,
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lambert_transfer(3, 4,
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'2027-01-01 00:00:00+00'::timestamptz,
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'2026-01-01 00:00:00+00'::timestamptz);
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-- ============================================================
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-- Test 9: Mini pork chop - 3x3 grid of departure/arrival dates
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-- All should return non-NULL results.
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-- ============================================================
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SELECT 'pork_chop_mini' AS test,
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dep_date::date AS dep,
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arr_date::date AS arr,
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round(lambert_c3(3, 4, dep_date, arr_date)::numeric, 1) AS c3
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FROM generate_series('2026-04-01'::timestamptz, '2026-06-01'::timestamptz, interval '30 days') dep_date
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CROSS JOIN generate_series('2027-01-01'::timestamptz, '2027-03-01'::timestamptz, interval '30 days') arr_date;
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