Ported ttut1 (#21)

* ttut1 * ttut1 done * ttut1 * ttut1 * ttut1 * ttut1 fixed
JuliaAstro · May 14, 2018 · 27cbb88 · 27cbb88
1 parent 8982cef
commit 27cbb88
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diff --git a/src/conversions.jl b/src/conversions.jl
@@ -383,15 +383,39 @@ julia> AstroTime.Epochs.tttdb(tt.jd1, tt.jd2, AstroTime.Epochs.deltatr(tdb))
     date, date1
 end
 
+"""
+    ttut1(jd1, jd2, dt)
+
+Transform a two-part Julian date from `TT` to `UT1`.
 
+# Example
+
+```jldoctest
+julia> tt = Epoch{tt}(2.4578265e6, 0.30440190993249416)
+2017-03-14T07:18:20.325 TT
+julia> AstroTime.Epochs.ttut1(tt.jd1, tt.jd2, AstroTime.Epochs.deltat(tt))
+(2.4578265e6, 0.30440190993249416)
+```
+"""
+@inline function ttut1(jd1, jd2, dt)
+     dtd = dt / SECONDS_PER_DAY
+     if jd1 > jd2
+        date = jd1
+        date1 = jd2 - dtd
+     else
+        date = jd1 - dtd
+        date1 = jd2
+    end
+    date, date1
+end
+
 """
     ut1tt(jd1, jd2, dt)
 
 Transform a two-part Julian date from `UT1` to `TT`.
 
 # Example
 
-```jldoctest
 julia> ut1 = Epoch{UT1}(2.4578265e6, 0.30440190993249416)
 2017-03-14T07:18:20.325 UT1
 julia> AstroTime.Epochs.ut1tt(ut1.jd1, ut1.jd2, AstroTime.Epochs.deltat(ut1))

diff --git a/test/runtests.jl b/test/runtests.jl
@@ -188,8 +188,11 @@ AstroTime.update()
         @test Epochs.tttdb(julian2(tt), julian1(tt), Δtr(tdb)) == ERFA.tttdb(julian2(tt), julian1(tt), Δtr(tdb))
 
         dt(ep) = Epochs.deltat(ep)
+        @test Epochs.ttut1(julian1(tt), julian2(tt), dt(tt)) == ERFA.ttut1(julian1(tt), julian2(tt), dt(tt))
+        @test Epochs.ttut1(julian2(tt), julian1(tt), dt(tt)) == ERFA.ttut1(julian2(tt), julian1(tt), dt(tt))
         @test Epochs.ut1tt(julian1(ut1), julian2(ut1), dt(ut1)) == ERFA.tttdb(julian1(ut1), julian2(ut1), dt(ut1))
         @test Epochs.ut1tt(julian2(ut1), julian1(ut1), dt(ut1)) == ERFA.tttdb(julian2(ut1), julian1(ut1), dt(ut1))
+
     end
     @testset "Leap Seconds" begin
         @test leapseconds(TTEpoch(1959,1,1)) == 0