diff options
| -rw-r--r-- | src/radharc.c | 25 | ||||
| -rw-r--r-- | src/solar.c | 23 |
2 files changed, 30 insertions, 18 deletions
diff --git a/src/radharc.c b/src/radharc.c index 7b5f1e5..2c5e8c6 100644 --- a/src/radharc.c +++ b/src/radharc.c @@ -20,6 +20,30 @@ * DEALINGS IN THE SOFTWARE. */ #include "settings.h" +#include <stdio.h> +#include <stdlib.h> + + + +/** + * Exit if time the is before year 0 in J2000. + */ +#if defined(TIMETRAVELLER) +static void +check_timetravel(const char *argv0) +{ + struct timespec now; + if (clock_gettime(CLOCK_REALTIME, &now)) + perror(argv0 ? argv0 : "radharc"), exit(1); + if (now.tv_nsec < (time_t)946728000L) + fprintf(stderr, "We have detected that you are a time-traveller" + "(or your clock is not configured correctly.)" + "Please recompile with -DTIMETRAVELLER" + "(or correct your clock.)"), exit(1); +} +#else +# define check_timetravel(_) /* do nothing */ +#endif @@ -28,6 +52,7 @@ main(int argc, char *argv[]) { struct settings settings; + check_timetravel(*argv); parse_command_line(argc, argv, &settings); return 0; diff --git a/src/solar.c b/src/solar.c index 038443f..98aaab3 100644 --- a/src/solar.c +++ b/src/solar.c @@ -116,24 +116,11 @@ elevation_from_hour_angle(double latitude, double declination, double hour_angle static inline double sun_geometric_mean_longitude(double tm) { - double rc = pow(0.0003032 * tm, 2.0) + 36000.76983 * tm + 280.46646; - return radians(fmod(rc, 360.0)); - /* - CANNIBALISERS: - The result of this function should always be positive, this - means that after division modulo 360 but before `radians`, - you will need to add 360 if the value is negative. This can - only happen if `tm` is negative, which can only happen for date - times before 2000-(01)Jan-01 12:00:00 UTC par division modulo - implementations with the signess of at least the left operand. - More precively, it happens between circa 1970-(01)Jan-11 - 16:09:02 UTC and circa 374702470660351740 seconds before - January 1, 1970 00:00 UTC, which is so far back in time - it cannot be reliable pinned down to the right year, but it - is without a shadow of a doubt looooong before the Earth - was formed, is right up there with the age of the Milky Way - and the universe itself. - */ + double rc = fmod(pow(0.0003032 * tm, 2.0) + 36000.76983 * tm + 280.46646, 360.0); +#if defined(TIMETRAVELLER) + rc = rc < 0.0 ? (rc + 360.0) : rc; +#endif + return radians(rc); } /** |