Standalone test (test/test_de_reader.c): generates a synthetic 12KB
DE binary with known Chebyshev coefficients, exercises header parsing,
polynomial evaluation at 5 domain points, Earth derivation via
center=99, Moon geocentric, layout validation, range/body error paths,
NAN sentinel, and garbage file rejection. 55 tests, no PG dependency.
Makefile: add `make test-de-reader` target; also includes the earlier
sat_code C++ -> pure C sgp4 migration that was missed from prior commits.
astro_math.h: document that ecliptic_to_equatorial/equatorial_to_ecliptic
are NOT safe for aliased (in-place) calls — equ[1] is written before
equ[2] reads ecl[1]. The vendored sgp4/sdp4.c has separate in-place
versions using a temp variable.
Three independent reviews (manual, failure-mode analysis, JPL spec
cross-reference) confirmed the mathematical core is correct. This
commit addresses defensive coding and operational behavior:
- Fix header byte-offset comments (12 groups = 144 bytes, not 156)
- Add layout validation before Chebyshev interpolation (prevent
buffer underread for bodies absent from a DE edition)
- Clamp Chebyshev argument to [-1,+1] with debug assertion for
values beyond 1e-10 tolerance (catches structural normalization
errors vs normal FP boundary rounding)
- Add O_CLOEXEC to prevent FD leaks to child processes
- Change GUC from PGC_SIGHUP to PGC_BACKEND to match actual
one-shot initialization behavior
- Fix provider consistency: planet_velocity_de() now accepts a
use_de flag to match the provider used for positions (rule 7)
- Optimize eph_de_moon() to use raw geocentric Moon (center=-1)
instead of computing Earth just to subtract it back out
- Pre-compute obliquity trig constants (verified to full precision)
- Tighten canary check from 0.9-1.1 AU to 0.97-1.04 AU
- Return NAN for missing constants (0.0 was ambiguous)
- Add _Static_assert for sizeof(double) == 8
- Remove unused HDR_* macros
- Zero Datum values before setting null flags in ephemeris_info
- Replace magic numbers with DE_MOON/DE_SUN constants
All 13 regression tests pass. Zero compiler warnings.
Clean-room DE binary reader (~400 lines C) with Chebyshev/Clenshaw
evaluation — no GPL dependency on jpl_eph. Per-backend lazy
initialization preserves PARALLEL SAFE. Existing VSOP87/ELP82B
functions stay IMMUTABLE; new _de() variants are STABLE with
automatic fallback to compiled-in ephemerides on any DE failure.
Implementation:
- de_reader.c: header parse, record seek, Clenshaw recurrence
- eph_provider.c: GUC (pg_orbit.ephemeris_path), lazy init,
ICRS-to-ecliptic frame rotation, on_proc_exit cleanup
- de_funcs.c: 11 new SQL functions (_de variants + diagnostics)
- Constant chain of custody rules 6-8 (frame rotation,
same-provider, AU consistency)
Extract observe_from_geocentric() to astro_math.h for shared use
by planet_funcs.c, moon_funcs.c, and de_funcs.c.
57 → 68 functions, 11 → 12 regression test suites, all passing.
Phase 1 — Stars, comets, Keplerian propagation:
- star_observe() / star_observe_safe(): fixed star alt/az via IAU 1976
precession, equatorial-to-horizontal transform
- kepler_propagate(): two-body Keplerian orbit propagation for
elliptic, parabolic, and hyperbolic orbits
- comet_observe(): observe comets/asteroids from orbital elements
- heliocentric type: ecliptic J2000 position (x, y, z in AU)
Phase 2 — VSOP87 planets, ELP82B Moon, Sun:
- planet_heliocentric(): VSOP87 heliocentric ecliptic J2000 positions
for Mercury through Neptune (Bretagnon & Francou, MIT)
- planet_observe(): full observation pipeline for any planet
- sun_observe(): Sun position from negated Earth VSOP87
- moon_observe(): ELP2000-82B lunar position (Chapront-Touzé, MIT)
- Clean-room precession (IAU 2006) and sidereal time (IERS 2010)
- elliptic_to_rectangular utility (Stellarium, MIT)
All Stellarium extractions are MIT-licensed, thread-safe (static
caching removed for PARALLEL SAFE), zero external data files.
All 9 regression tests pass (90ms total).
