out of order rise/transit/set times

[GorillaSapiens]

Attempting to use libnova 0.15.0 near the poles, I get many anomalous outputs from ln_get_solar_rst(). Generally, I get rise/transit/set times that do not occur in order. My expectation is that rise/transit/set should be in order increasing in time.

Please see example code and output attached.

$ uname -a
Linux incursion 5.13.0-30-generic #33-Ubuntu SMP Fri Feb 4 17:03:31 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

(cd libnova-0.15.0/src; gcc -c .c -I.)
ar r libnova.a libnova-0.15.0/src/.o
gcc -g -Wall -Ofast tester.c libnova.a -I libnova-0.15.0/src -lm -o tester

[GorillaSapiens]

not sure that attachment happened.

#include <stdio.h>
#include <stdlib.h>

#include <math.h>

#include <libnova/solar.h>
#include <libnova/lunar.h>
#include <libnova/julian_day.h>
#include <libnova/rise_set.h>
#include <libnova/transform.h>

int ln_get_solar_astronomical_rst(
double JD,
struct ln_lnlat_posn * observer,
struct ln_rst_time * rst)
{
return ln_get_solar_rst_horizon(
JD, observer, LN_SOLAR_ASTRONOMICAL_HORIZON, rst);
}

int ln_get_solar_civil_rst(
double JD,
struct ln_lnlat_posn * observer,
struct ln_rst_time * rst)
{
return ln_get_solar_rst_horizon (
JD, observer, LN_SOLAR_CIVIL_HORIZON, rst);
}

int ln_get_solar_nautical_rst(
double JD,
struct ln_lnlat_posn * observer,
struct ln_rst_time * rst)
{
return ln_get_solar_rst_horizon (
JD, observer, LN_SOLAR_NAUTIC_HORIZON, rst);
}

static void print_date (char *title, struct ln_zonedate *date)
{
printf("%s\t%04d-%02d-%02d %02d:%02d:%02.6f\n",
title,
date->years, date->months, date->days,
date->hours, date->minutes, date->seconds);
}

int main (int argc, const char *argv[])
{
struct ln_equ_posn equ;
struct ln_rst_time rst;
struct ln_zonedate rise, set, transit;
struct ln_lnlat_posn observer;
struct ln_helio_posn pos;
double JD;

/* observers location (nearish south pole), used to calc rst /
observer.lat = -85.0; / 85.00 S /
observer.lng = 115.0; / 115.00 E */

/* get Julian day from local time */
//JD = ln_get_julian_from_sys();
JD = 2459649.399739; // around 2022-03-01 16:36 US/Eastern

for (int i = 0; i < 366; i++, JD += 1.0) { // one year
/* geometric coordinates */
ln_get_solar_geom_coords(JD, &pos);

  /* ra, dec */
  ln_get_solar_equ_coords(JD, &equ);

  if (ln_get_solar_rst(JD, &observer, &rst) == 0) {
     if (!(rst.rise < rst.transit && rst.transit < rst.set)) {
        printf("=== SOLAR ANOMOLY JD=%f\n", JD);

        ln_get_local_date(rst.rise, &rise);
        ln_get_local_date(rst.transit, &transit);
        ln_get_local_date(rst.set, &set);
        print_date("Rise", &rise);
        print_date("Transit", &transit);
        print_date("Set", &set);
        printf("\n");
     }
  }

  if (ln_get_solar_civil_rst(JD, &observer, &rst) == 0) {
     if (!(rst.rise < rst.transit && rst.transit < rst.set)) {
        printf("=== CIVIL ANOMOLY JD=%f\n", JD);

        ln_get_local_date(rst.rise, &rise);
        ln_get_local_date(rst.transit, &transit);
        ln_get_local_date(rst.set, &set);
        print_date("Rise", &rise);
        print_date("Transit", &transit);
        print_date("Set", &set);
        printf("\n");
     }
  }

  if (ln_get_solar_nautical_rst(JD, &observer, &rst) == 0) {
     if (!(rst.rise < rst.transit && rst.transit < rst.set)) {
        printf("=== NAUTICAL ANOMOLY JD=%f\n", JD);

        ln_get_local_date(rst.rise, &rise);
        ln_get_local_date(rst.transit, &transit);
        ln_get_local_date(rst.set, &set);
        print_date("Rise", &rise);
        print_date("Transit", &transit);
        print_date("Set", &set);
        printf("\n");
     }
  }

  if (ln_get_solar_astronomical_rst(JD, &observer, &rst) == 0) {
     if (!(rst.rise < rst.transit && rst.transit < rst.set)) {
        printf("=== ASTRONOMICAL ANOMOLY JD=%f\n", JD);

        ln_get_local_date(rst.rise, &rise);
        ln_get_local_date(rst.transit, &transit);
        ln_get_local_date(rst.set, &set);
        print_date("Rise", &rise);
        print_date("Transit", &transit);
        print_date("Set", &set);
        printf("\n");
     }
  }

}

return 0;
}

=== SOLAR ANOMOLY JD=2459649.399739
Rise 2022-03-11 13:23:30.581432
Transit 2022-03-10 23:28:57.943031
Set 2022-03-11 09:39:48.453349

=== SOLAR ANOMOLY JD=2459650.399739
Rise 2022-03-12 13:53:39.632332
Transit 2022-03-11 23:28:42.162428
Set 2022-03-12 09:09:24.728540

=== SOLAR ANOMOLY JD=2459651.399739
Rise 2022-03-13 14:21:23.778204
Transit 2022-03-12 23:28:26.064387
Set 2022-03-13 08:41:20.414562

=== SOLAR ANOMOLY JD=2459652.399739
Rise 2022-03-14 14:46:11.559995
Transit 2022-03-13 23:28:9.670309
Set 2022-03-14 08:16:11.675089

=== SOLAR ANOMOLY JD=2459653.399739
Rise 2022-03-15 15:08:55.096233
Transit 2022-03-14 23:27:53.002084
Set 2022-03-15 07:53:7.133172

=== SOLAR ANOMOLY JD=2459654.399739
Rise 2022-03-16 15:30:10.024340
Transit 2022-03-15 23:27:36.082320
Set 2022-03-16 07:31:31.477798

=== SOLAR ANOMOLY JD=2459655.399739
Rise 2022-03-17 15:50:20.278770
Transit 2022-03-16 23:27:18.934274
Set 2022-03-17 07:11:1.016880

=== SOLAR ANOMOLY JD=2459656.399739
Rise 2022-03-18 16:09:42.813080
Transit 2022-03-17 23:27:1.581763
Set 2022-03-18 06:51:19.028521

=== SOLAR ANOMOLY JD=2459657.399739
Rise 2022-03-19 16:28:30.341384
Transit 2022-03-18 23:26:44.049048
Set 2022-03-19 06:32:13.045962

=== SOLAR ANOMOLY JD=2459658.399739
Rise 2022-03-20 16:46:52.934598
Transit 2022-03-19 23:26:26.360671
Set 2022-03-20 06:13:33.276216

=== CIVIL ANOMOLY JD=2459688.399739
Rise 2022-04-18 23:26:39.871923
Transit 2022-04-18 23:18:2.151657
Set 2022-04-18 23:04:22.485172

=== SOLAR ANOMOLY JD=2459844.399739
Rise 2022-09-22 16:41:5.323167
Transit 2022-09-21 23:11:41.743743
Set 2022-09-22 05:33:23.168549

=== SOLAR ANOMOLY JD=2459845.399739
Rise 2022-09-23 16:22:56.847316
Transit 2022-09-22 23:11:20.659729
Set 2022-09-23 05:51:12.111815

=== SOLAR ANOMOLY JD=2459846.399739
Rise 2022-09-24 16:04:30.058952
Transit 2022-09-23 23:10:59.701766
Set 2022-09-24 06:09:17.441595

=== SOLAR ANOMOLY JD=2459847.399739
Rise 2022-09-25 15:45:37.169704
Transit 2022-09-24 23:10:38.887556
Set 2022-09-25 06:27:47.327186

=== SOLAR ANOMOLY JD=2459848.399739
Rise 2022-09-26 15:26:8.697909
Transit 2022-09-25 23:10:18.234198
Set 2022-09-26 06:46:51.563104

=== SOLAR ANOMOLY JD=2459849.399739
Rise 2022-09-27 15:05:52.498309
Transit 2022-09-26 23:09:57.758389
Set 2022-09-27 07:06:42.558294

=== SOLAR ANOMOLY JD=2459850.399739
Rise 2022-09-28 14:44:32.128952
Transit 2022-09-27 23:09:37.476503
Set 2022-09-28 07:27:36.983958

=== SOLAR ANOMOLY JD=2459851.399739
Rise 2022-09-29 14:21:43.854176
Transit 2022-09-28 23:09:17.404956
Set 2022-09-29 07:49:58.786336

=== SOLAR ANOMOLY JD=2459852.399739
Rise 2022-09-30 13:56:50.520011
Transit 2022-09-29 23:08:57.560163
Set 2022-09-30 08:14:25.332435

=== SOLAR ANOMOLY JD=2459853.399739
Rise 2022-10-01 13:28:47.073258
Transit 2022-09-30 23:08:37.959103
Set 2022-10-01 08:42:1.940871

=== SOLAR ANOMOLY JD=2459854.399739
Rise 2022-10-02 12:55:17.735937
Transit 2022-10-01 23:08:18.619558
Set 2022-10-02 09:15:4.881392

=== SOLAR ANOMOLY JD=2459855.399739
Rise 2022-10-03 12:09:44.475365
Transit 2022-10-02 23:07:59.560156
Set 2022-10-03 10:00:14.021194

=== SOLAR ANOMOLY JD=2459856.399739
Rise 2022-10-04 09:46:17.784611
Transit 2022-10-03 23:07:40.800572
Set 2022-10-04 12:24:43.153452

=== SOLAR ANOMOLY JD=2460014.399739
Rise 2023-03-11 13:18:42.077425
Transit 2023-03-10 23:28:57.171158
Set 2023-03-11 09:44:24.137551