Fix double counting of leap seconds in MJD/JDE initializers in UTC

Closes #302
nyx-space · Oct 6, 2024 · 9436c67 · 9436c67
1 parent 64b4767
commit 9436c67
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Showing 2 changed files with 43 additions and 20 deletions.
diff --git a/src/epoch/initializers.rs b/src/epoch/initializers.rs
@@ -102,21 +102,18 @@ impl Epoch {
 
     #[must_use]
     pub fn from_mjd_tai(days: f64) -> Self {
+        Self::from_mjd_in_time_scale(days, TimeScale::TAI)
+    }
+
+    pub fn from_mjd_in_time_scale(days: f64, time_scale: TimeScale) -> Self {
         assert!(
             days.is_finite(),
             "Attempted to initialize Epoch with non finite number"
         );
-        Self::from_tai_duration((days - MJD_J1900) * Unit::Day)
-    }
-
-    pub fn from_mjd_in_time_scale(days: f64, time_scale: TimeScale) -> Self {
-        // always refer to TAI/mjd
-        let mut e = Self::from_mjd_tai(days);
-        if time_scale.uses_leap_seconds() {
-            e.duration += e.leap_seconds(true).unwrap_or(0.0) * Unit::Second;
+        Self {
+            duration: (days - MJD_J1900) * Unit::Day,
+            time_scale,
         }
-        e.time_scale = time_scale;
-        e
     }
 
     #[must_use]
@@ -142,21 +139,18 @@ impl Epoch {
 
     #[must_use]
     pub fn from_jde_tai(days: f64) -> Self {
+        Self::from_jde_in_time_scale(days, TimeScale::TAI)
+    }
+
+    fn from_jde_in_time_scale(days: f64, time_scale: TimeScale) -> Self {
         assert!(
             days.is_finite(),
             "Attempted to initialize Epoch with non finite number"
         );
-        Self::from_tai_duration((days - MJD_J1900 - MJD_OFFSET) * Unit::Day)
-    }
-
-    fn from_jde_in_time_scale(days: f64, time_scale: TimeScale) -> Self {
-        // always refer to TAI/jde
-        let mut e = Self::from_jde_tai(days);
-        if time_scale.uses_leap_seconds() {
-            e.duration += e.leap_seconds(true).unwrap_or(0.0) * Unit::Second;
+        Self {
+            duration: (days - MJD_J1900 - MJD_OFFSET) * Unit::Day,
+            time_scale,
         }
-        e.time_scale = time_scale;
-        e
     }
 
     #[must_use]

diff --git a/tests/epoch.rs b/tests/epoch.rs
@@ -2143,3 +2143,32 @@ fn regression_test_gh_317() {
         nanos
     );
 }
+
+#[test]
+fn regression_test_gh_302() {
+    let days = 60660.0;
+    let mjd = Epoch::from_mjd_utc(days);
+    let extra_duration = 2 * Unit::Hour + 5 * Unit::Minute + 8 * Unit::Second;
+    let mjd_plus_duration = mjd + extra_duration;
+    assert_eq!(
+        mjd_plus_duration.to_mjd_utc_days(),
+        days + extra_duration.to_unit(Unit::Day)
+    );
+    assert_eq!(
+        mjd_plus_duration.to_gregorian_str(TimeScale::UTC),
+        "2024-12-16T02:05:08 UTC"
+    );
+
+    // Repeat with JDE
+    let jde = Epoch::from_jde_utc(days + MJD_OFFSET);
+    let extra_duration = 2 * Unit::Hour + 5 * Unit::Minute + 8 * Unit::Second;
+    let jde_plus_duration = jde + extra_duration;
+    assert_eq!(
+        mjd_plus_duration.to_mjd_utc_days(),
+        days + extra_duration.to_unit(Unit::Day)
+    );
+    assert_eq!(
+        jde_plus_duration.to_gregorian_str(TimeScale::UTC),
+        "2024-12-16T02:05:08 UTC"
+    );
+}