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It's surprisingly tricky to print a time rounded to the nearest millisecond, second, or minute using the C code. I saw a case where positions.c printed '2020-07-09 04:29:60'. Because printing a date/time is a basic need of an astronomy program, I added the new function Astronomy_FormatTime to do this. All the demo programs use this new function, which required me to update the correct reference output for the unit tests.
63 lines
2.0 KiB
C
63 lines
2.0 KiB
C
/*
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positions.c - by Don Cross - 2019-06-11
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Example C program for Astronomy Engine:
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https://github.com/cosinekitty/astronomy
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Given an observer's geographic latitude and longitude,
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and an optional date and time, this program displays the
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equatorial and horizontal coordinates of the Sun, Moon, and planets.
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If the date and time is omitted from the command line, the
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program uses the computer's current date and time.
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*/
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#include <stdio.h>
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#include "astro_demo_common.h"
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int main(int argc, const char *argv[])
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{
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static const astro_body_t body[] = {
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BODY_SUN, BODY_MOON, BODY_MERCURY, BODY_VENUS, BODY_MARS,
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BODY_JUPITER, BODY_SATURN, BODY_URANUS, BODY_NEPTUNE, BODY_PLUTO
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};
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int error;
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astro_observer_t observer;
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astro_time_t time;
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astro_equatorial_t equ_2000, equ_ofdate;
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astro_horizon_t hor;
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int i;
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int num_bodies = sizeof(body) / sizeof(body[0]);
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error = ParseArgs(argc, argv, &observer, &time);
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if (error)
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return error;
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printf("UTC date = ");
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PrintTime(time);
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printf("\n");
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printf("BODY RA DEC AZ ALT\n");
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for (i=0; i < num_bodies; ++i)
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{
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equ_2000 = Astronomy_Equator(body[i], &time, observer, EQUATOR_J2000, ABERRATION);
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if (equ_2000.status != ASTRO_SUCCESS)
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{
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fprintf(stderr, "ERROR: Astronomy_Equator returned status %d trying to get J2000 coordinates.\n", equ_2000.status);
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return 1;
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}
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equ_ofdate = Astronomy_Equator(body[i], &time, observer, EQUATOR_OF_DATE, ABERRATION);
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if (equ_ofdate.status != ASTRO_SUCCESS)
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{
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fprintf(stderr, "ERROR: Astronomy_Equator returned status %d trying to get coordinates of date.\n", equ_ofdate.status);
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return 1;
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}
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hor = Astronomy_Horizon(&time, observer, equ_ofdate.ra, equ_ofdate.dec, REFRACTION_NORMAL);
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printf("%-8s %8.2lf %8.2lf %8.2lf %8.2lf\n", Astronomy_BodyName(body[i]), equ_2000.ra, equ_2000.dec, hor.azimuth, hor.altitude);
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}
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return 0;
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}
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