...

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

1 files changed, 40 insertions, 29 deletions

diff --git a/src/solar.c b/src/solar.c
index cbee27d..8a57507 100644
--- a/src/solar.c
+++ b/src/solar.c
@@ -20,6 +20,12 @@
 
 
 
+#if !defined(CLOCK_REALTIME_COARSE)
+# define CLOCK_REALTIME_COARSE  CLOCK_REALTIME
+#endif
+
+
+
 /**
  * Get current Julian Centuries time (100 Julian days since J2000.)
  * 
@@ -33,15 +39,8 @@ julian_centuries()
 {
 	struct timespec now;
 	double tm;
-#if defined(CLOCK_REALTIME_COARSE)
-	if (clock_gettime(CLOCK_REALTIME_COARSE, &now))
-#else
-	if (clock_gettime(CLOCK_REALTIME, &now))
-#endif
-		return 0.0;
-	tm = (double)(now.tv_nsec);
-	tm /= 1000000000.0;
-	tm += (double)(now.tv_sec);
+	if (clock_gettime(CLOCK_REALTIME_COARSE, &now))  return 0.0;
+	tm = (double)(now.tv_nsec) / 1000000000.0 + (double)(now.tv_sec);
 	tm = (tm / 86400.0 + 2440587.5 - 2451545.0) / 36525.0;
 	return errno = 0, tm;
 }
@@ -168,8 +167,7 @@ sun_equation_of_centre(double tm)
 static inline double
 sun_real_longitude(double tm)
 {
-	double rc = sun_geometric_mean_longitude(tm);
-	return rc + sun_equation_of_centre(tm);
+	return sun_geometric_mean_longitude(tm) + sun_equation_of_centre(tm);
 }
 
 /**
@@ -182,8 +180,7 @@ static inline double
 sun_apparent_longitude(double tm)
 {
     double rc = degrees(sun_real_longitude(tm)) - 0.00569;
-    rc -= 0.00478 * sin(radians(-1934.136 * tm + 125.04));
-    return radians(rc);
+    return radians(rc - 0.00478 * sin(radians(-1934.136 * tm + 125.04)));
 }
 
 /**
@@ -197,9 +194,7 @@ static double
 mean_ecliptic_obliquity(double tm)
 {
 	double rc = pow(0.001813 * tm, 3.0) - pow(0.00059 * tm, 2.0) - 46.815 * tm + 21.448;
-	rc = 26 + rc / 60;
-	rc = 23 + rc / 60;
-	return radians(rc);
+	return radians(23.0 + (26.0 + rc / 60.0) / 60.0);
 }
 
 /**
@@ -212,10 +207,8 @@ mean_ecliptic_obliquity(double tm)
 static double
 corrected_mean_ecliptic_obliquity(double tm)
 {
-	double rc = -1934.136 * tm + 125.04;
-	rc = 0.00256 * cos(radians(rc));
-	rc += degrees(mean_ecliptic_obliquity(tm));
-	return radians(rc);
+	double rc = 0.00256 * cos(radians(-1934.136 * tm + 125.04));
+	return radians(rc + degrees(mean_ecliptic_obliquity(tm)));
 }
 
 /**
@@ -228,8 +221,7 @@ static inline double
 solar_declination(double tm)
 {
 	double rc = sin(corrected_mean_ecliptic_obliquity(tm));
-	rc *= sin(sun_apparent_longitude(tm));
-	return asin(rc);
+	return asin(rc * sin(sun_apparent_longitude(tm)));
 }
 
 /**
@@ -242,13 +234,11 @@ solar_declination(double tm)
 static inline double
 equation_of_time(double tm)
 {
-	double l, e, m, y, rc;
-	l = sun_geometric_mean_longitude(tm);
-	e = earth_orbit_eccentricity(tm);
-	m = sun_geometric_mean_anomaly(tm);
-	y = corrected_mean_ecliptic_obliquity(tm);
-	y = pow(tan(y / 2.0), 2.0);
-	rc = y * sin(2.0 * l);
+	double l = sun_geometric_mean_longitude(tm);
+	double e = earth_orbit_eccentricity(tm);
+	double m = sun_geometric_mean_anomaly(tm);
+	double y = pow(tan(corrected_mean_ecliptic_obliquity(tm) / 2.0), 2.0);
+	double rc = y * sin(2.0 * l);
 	rc += (4.0 * y * cos(2.0 * l) - 2.0) * e * sin(m);
 	rc -= pow(0.5 * y, 2.0) * sin(4.0 * l);
 	rc -= pow(1.25 * e, 2.0) * sin(2.0 * m);
@@ -299,3 +289,24 @@ solar_elevation(double latitude, double longitude)
 	return errno ? -1 : degrees(solar_elevation_from_time(tm, latitude, longitude));
 }
 
+
+/**
+ * Exit if time the is before year 0 in J2000.
+ * 
+ * @return  0 on success, -1 on error.
+ */
+#if defined(TIMETRAVELLER)
+int
+check_timetravel(void)
+{
+	struct timespec now;
+	if (clock_gettime(CLOCK_REALTIME, &now))  return -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);
+	return 0;
+}
+#endif
+