Merge 6a0213d into 1894edf

JuliaAstro · May 12, 2018 · d3bc19d · d3bc19d
2 parents 1894edf + 6a0213d
commit d3bc19d
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diff --git a/src/conversions.jl b/src/conversions.jl
@@ -357,6 +357,32 @@ end
     32.184 + leapsec - ΔUT1
 end
 
+"""
+    tttdb(jd1, jd2, dtr)
+
+Transform a two-part Julian date from `TT` to `TDB`.
+
+# Example
+
+```jldoctest
+julia> tt = Epoch{TT}(2.4578265e6, 0.30440190993249416)
+2017-03-14T07:18:20.325 TT
+julia> AstroTime.Epochs.tttdb(tt.jd1, tt.jd2, AstroTime.Epochs.deltatr(tdb))
+(2.4578265e6, 0.30440190993249416)
+```
+"""
+@inline function tttdb(jd1, jd2, dtr)
+    dtrd = dtr / SECONDS_PER_DAY
+        if jd1 > jd2
+            date = jd1
+            date1 = jd2 + dtrd
+        else
+            date = jd1 + dtrd
+            date1 = jd2
+        end
+        date, date1
+end
+
 # TAI <-> UTC
 @transform UTC TAI ep begin
     jd1, jd2 = julian1(ep), julian2(ep)
@@ -491,4 +517,3 @@ Epoch{T}(ep::Epoch{T}) where {T} = ep
     end
     ex
 end
-
diff --git a/test/runtests.jl b/test/runtests.jl
@@ -184,6 +184,8 @@ AstroTime.update()
         @test Epochs.dtdb(julian1(tdb), julian2(tdb), 0.0, 0.0, 0.0, 0.0) == ERFA.dtdb(julian1(tdb), julian2(tdb), 0.0, 0.0, 0.0, 0.0)
         @test Epochs.tdbtt(julian1(tdb), julian2(tdb), Δtr(tdb)) == ERFA.tdbtt(julian1(tdb), julian2(tdb), Δtr(tdb))
         @test Epochs.tdbtt(julian2(tdb), julian1(tdb), Δtr(tdb)) == ERFA.tdbtt(julian2(tdb), julian1(tdb), Δtr(tdb))
+        @test Epochs.tttdb(julian1(tt), julian2(tt), Δtr(tdb)) == ERFA.tttdb(julian1(tt), julian2(tt), Δtr(tdb))
+        @test Epochs.tttdb(julian2(tt), julian1(tt), Δtr(tdb)) == ERFA.tttdb(julian2(tt), julian1(tt), Δtr(tdb))
     end
     @testset "Leap Seconds" begin
         @test leapseconds(TTEpoch(1959,1,1)) == 0