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https://github.com/cosinekitty/astronomy.git
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e827c257b4
The following C functions now support searching
in forward or reverse chronological order:
Astronomy_SearchRiseSet
Astronomy_SearchAltitude
Astronomy_SearchHourAngleEx
The function Astronomy_SearchHourAngleEx replaces
Astronomy_SearchHourAngle, adding a new `direction` parameter.
A #define for Astronomy_SearchHourAngle preserves backward
compatibility for older code.
Implementation notes:
Astronomy_SearchRiseSet and Astronomy_SearchAltitude used
to call a private function InternalSearchAltitude.
That function has been split into two functions:
BackwardSearchAltitude and ForwardSearchAltitude,
for searching both directions in time.
Fixed a bug where it was possible to report a successful
altitude event that went outside the time limit specified
by `limitDays`.
68 lines
1.9 KiB
C
68 lines
1.9 KiB
C
/*
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culminate.c - by Don Cross - 2019-06-18
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Example C program for Astronomy Engine:
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https://github.com/cosinekitty/astronomy
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This example program shows how to calculate the time
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the Sun, Moon, and planets will next reach their highest point in the sky
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as seen by an observer at a given location on the Earth.
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This is called culmination, and is found by finding when
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each body's "hour angle" is 0.
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Having an hour angle of 0 is another way of saying that the body is
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crossing the meridian, the imaginary semicircle in the sky that passes
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from due north on the horizon, through the zenith (straight up),
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toward due south on the horizon. At this moment the body appears to
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have an azimuth of either 180 degrees (due south) or 0 (due north).
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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 PrintEvent(const char *name, astro_hour_angle_t evt)
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{
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printf("%-8s : ", name);
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if (evt.status == ASTRO_SUCCESS)
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{
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PrintTime(evt.time);
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printf(" altitude=%6.2lf azimuth=%6.2lf\n", evt.hor.altitude, evt.hor.azimuth);
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return 0;
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}
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else
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{
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printf("ERROR %d\n", evt.status);
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return 1;
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}
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}
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int main(int argc, const char *argv[])
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{
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static const astro_body_t bodies[] =
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{
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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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static const int nbodies = sizeof(bodies) / sizeof(bodies[0]);
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astro_observer_t observer;
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astro_time_t time;
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astro_hour_angle_t evt;
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int i;
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if (ParseArgs(argc, argv, &observer, &time))
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return 1;
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printf("search : ");
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PrintTime(time);
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printf("\n");
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for (i=0; i < nbodies; ++i)
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{
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evt = Astronomy_SearchHourAngleEx(bodies[i], observer, 0.0, time, +1);
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PrintEvent(Astronomy_BodyName(bodies[i]), evt);
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}
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return 0;
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}
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