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I was experimenting with an alternative way to calculate Pluto's position. That idea didn't work out, but in the process, I did make some changes I want to keep: 1. A typecast in generate/codegen.c that eliminates a build warning in Windows (Visual Studio 2015). 2. Expanded generate/vsop/vsop.c to calculate both position and velocity vectors. This was tricky to get working, and could come in handy.
101 lines
2.9 KiB
C
101 lines
2.9 KiB
C
/*
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vsop.h - Don Cross - 2019-03-24
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Loads and calculates planetary positions using VSOP87 analytic models.
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See: https://en.wikipedia.org/wiki/VSOP_(planets)
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*/
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#ifndef __DDC_VSOP_H
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#define __DDC_VSOP_H
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typedef enum
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{
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VSOP_INVALID_VERSION = -1,
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VSOP_ELLIPTIC_J2000 = 0, /* VSOP87.* files */
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VSOP_HELIO_RECT_J2000 = 1, /* VSOP87A.* files */
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VSOP_HELIO_SPHER_J2000 = 2, /* VSOP87B.* files */
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VSOP_HELIO_RECT_DATE = 3, /* VSOP87C.* files */
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VSOP_HELIO_SPHER_DATE = 4, /* VSOP87D.* files */
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VSOP_BARY_RECT_J2000 = 5, /* VSOP87E.* files */
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}
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vsop_version_t;
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typedef struct
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{
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double amplitude;
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double phase;
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double frequency;
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}
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vsop_term_t;
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typedef struct
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{
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int nterms_total; /* total number of terms in the VSOP87 model */
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int nterms_calc; /* number of terms at the front to actually calculate (allows faster, lower-res calc) */
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vsop_term_t *term;
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}
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vsop_series_t;
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#define VSOP_MAX_SERIES 10
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typedef struct
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{
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int nseries_total; /* total number of series in the VSOP87 model */
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int nseries_calc; /* number of series at the front to actually calculate (allows faster, lower-res calc) */
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vsop_series_t series[VSOP_MAX_SERIES];
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}
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vsop_formula_t;
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#define VSOP_MIN_COORDS 3
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#define VSOP_MAX_COORDS 6
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typedef enum /* values created for compatibility with NOVAS; these are *NOT* the body codes used by VSOP! */
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{
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VSOP_INVALID_BODY = -1,
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VSOP_MERCURY = 0,
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VSOP_VENUS = 1,
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VSOP_EMB = 2, /* Earth/Moon barycenter, to match NOVAS */
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VSOP_MARS = 3,
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VSOP_JUPITER = 4,
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VSOP_SATURN = 5,
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VSOP_URANUS = 6,
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VSOP_NEPTUNE = 7,
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/* Remaining values are not supported by VSOP. */
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/* Placeholders for NOVAS. */
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VSOP_PLUTO = 8,
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VSOP_GM = 9,
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VSOP_SUN = 10,
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/* Extensions beyond what NOVAS supports. */
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VSOP_EARTH = 11,
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VSOP_MOON = 12,
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VSOP_SSB = 13
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}
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vsop_body_t;
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#define VSOP_BODY_LIMIT 14
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typedef struct
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{
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vsop_version_t version;
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vsop_body_t body;
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int ncoords;
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vsop_formula_t formula[VSOP_MAX_COORDS];
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}
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vsop_model_t;
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void VsopInit(vsop_model_t *model); /* optional usage: create invalid null model that can be safely freed */
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void VsopFreeModel(vsop_model_t *model);
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int VsopLoadModel(vsop_model_t *model, const char *inFileName);
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int VsopCalcPos(const vsop_model_t *model, double tt, double pos[3]);
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int VsopCalcPosVel(const vsop_model_t *model, double tt, double pos[3], double vel[3]);
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int VsopTruncate(vsop_model_t *model, double tt1, double tt2, double amplitudeThreshold);
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void VsopTrim(vsop_model_t *model); /* delete trailing empty series */
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int VsopTermCount(const vsop_model_t *model);
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int VsopWriteTrunc(const vsop_model_t *model, const char *outFileName);
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int VsopReadTrunc(vsop_model_t *model, const char *inFileName);
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#endif /* __DDC_VSOP_H */
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