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Generate JSON ephemeris using J2000 dates instead of Julian dates.

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This commit is contained in:
Don Cross
2020-07-11 10:10:27 -04:00
parent c563237399
commit bccffc0055
1 changed files with 15 additions and 11 deletions
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26
generate/generate.c
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@@ -2724,7 +2724,7 @@ fail:
/*------------------------------------------------------------------------------------------------*/
static int ParseDate(const char *text, double *jd)
static int ParseDate(const char *text, double *tt)
{
int error = 1;
int year, month, day;
@@ -2732,7 +2732,7 @@ static int ParseDate(const char *text, double *jd)
if (3 != sscanf(text, "%d-%d-%d", &year, &month, &day))
FAIL("ParseDate: text '%s' is not valid. Must be formatted as yyyy-mm-dd.\n", text);
*jd = julian_date((short)year, (short)month, (short)day, 12.0);
*tt = julian_date((short)year, (short)month, (short)day, 12.0) - 2451545.0;
error = 0;
fail:
return error;
@@ -2775,33 +2775,37 @@ static int EphemerisJson(const char *filename, const char *date1, const char *da
};
static const int nbodies = (int)(sizeof(bodylist) / sizeof(bodylist[0]));
int i, error;
double jd, jd1, jd2;
double tt, tt2;
gravsim_body_state_t bs;
FILE *outfile = NULL;
CHECK(OpenEphem());
CHECK(ParseDate(date1, &jd1));
CHECK(ParseDate(date2, &jd2));
CHECK(ParseDate(date1, &tt));
CHECK(ParseDate(date2, &tt2));
outfile = fopen(filename, "wt");
if (outfile == NULL)
FAIL("EphemerisJson: Cannot open output file: %s\n", filename);
fprintf(outfile, "{\"jd1\":%lf, \"jd2\":%lf, \"delta_days\":%lf, \"data\":[\n", jd1, jd2, delta_days);
for (jd = jd1; jd <= jd2; jd += delta_days)
fprintf(outfile, "{\"tt1\":%0.8lf, \"tt2\":%0.8lf, \"dt\":%0.8lf, \"data\":[\n", tt, tt2, delta_days);
for(;;)
{
fprintf(outfile," {\"jd\":%17.8lf, \"body\":{\n", jd);
fprintf(outfile," {\"tt\":%0.8lf, \"body\":{\n", tt);
for (i=0; i < nbodies; ++i)
{
CHECK(BodyState(jd, bodylist[i], &bs));
CHECK(BodyState(tt + 2451545.0, bodylist[i], &bs));
fprintf(outfile, " %s:{\"pos\":[%24.16le,%24.16le,%24.16le], \"vel\":[%24.16le,%24.16le,%24.16le]}%s\n",
QuotedBodyName(bodylist[i]),
bs.pos[0], bs.pos[1], bs.pos[2],
bs.vel[0], bs.vel[1], bs.vel[2],
(i+1 < nbodies) ? "," : "");
}
fprintf(outfile, " }}%s\n", (jd + delta_days <= jd2) ? "," : "");
fprintf(outfile, " }}");
tt += delta_days;
if (tt > tt2)
break;
fprintf(outfile, ",\n");
}
fprintf(outfile, "]}\n");
fprintf(outfile, "\n]}\n");
error = 0;
fail:
ephem_close();