func ExampleParallax() {
// Example 47.a, p. 342.
_, _, Δ := moonposition.Position(julian.CalendarGregorianToJD(1992, 4, 12))
π := moonposition.Parallax(Δ)
fmt.Printf("π = %.6f\n", π.Deg())
// Output:
// π = 0.991990
}
func TestParallax(t *testing.T) {
// test case from ch 40, p. 280
got := moonposition.Parallax(.37276 * base.AU).Sec()
want := 23.592
if math.Abs(got-want) > .001 {
t.Error(got, want)
}
}
// Lacking a worked example from the text, test using meeus/moonposition.
func TestPerigeeParallax(t *testing.T) {
got := apsis.PerigeeParallax(1997.93)
_, _, d := moonposition.Position(apsis.Perigee(1997.93))
want := moonposition.Parallax(d)
Δ := math.Abs((got - want).Sec())
// for this case anyway it's within a tenth of an arc second
if Δ > .1 {
t.Fatal("got", got, "want (about)", want)
}
}