// Exercise, p. 136.
func TestPosition(t *testing.T) {
eqFrom := &coord.Equatorial{
base.NewRA(2, 31, 48.704).Rad(),
base.NewAngle(false, 89, 15, 50.72).Rad(),
}
eqTo := &coord.Equatorial{}
mα := base.NewHourAngle(false, 0, 0, 0.19877)
mδ := base.NewAngle(true, 0, 0, 0.0152)
for _, tc := range []struct {
α, δ string
jde float64
}{
{"1 22 33.90", "88 46 26.18", base.BesselianYearToJDE(1900)},
{"3 48 16.43", "89 27 15.38", base.JulianYearToJDE(2050)},
{"5 53 29.17", "89 32 22.18", base.JulianYearToJDE(2100)},
} {
epochTo := base.JDEToJulianYear(tc.jde)
precess.Position(eqFrom, eqTo, 2000.0, epochTo, mα, mδ)
αStr := fmt.Sprintf("%.2x", base.NewFmtRA(eqTo.RA))
δStr := fmt.Sprintf("%.2x", base.NewFmtAngle(eqTo.Dec))
if αStr != tc.α {
t.Fatal("got:", αStr, "want:", tc.α)
}
if δStr != tc.δ {
t.Fatal(δStr)
}
}
}
// Exercise, p. 136.
func TestPosition(t *testing.T) {
eqFrom := &coord.Equatorial{
unit.NewRA(2, 31, 48.704),
unit.NewAngle(' ', 89, 15, 50.72),
}
eqTo := &coord.Equatorial{}
mα := unit.HourAngleFromSec(0.19877)
mδ := unit.AngleFromSec(-0.0152)
for _, tc := range []struct {
α, δ string
jde float64
}{
{"1ʰ22ᵐ33.90ˢ", "88°46′26.18″", base.BesselianYearToJDE(1900)},
{"3ʰ48ᵐ16.43ˢ", "89°27′15.38″", base.JulianYearToJDE(2050)},
{"5ʰ53ᵐ29.17ˢ", "89°32′22.18″", base.JulianYearToJDE(2100)},
} {
epochTo := base.JDEToJulianYear(tc.jde)
precess.Position(eqFrom, eqTo, 2000.0, epochTo, mα, mδ)
αStr := fmt.Sprintf("%.2s", sexa.FmtRA(eqTo.RA))
δStr := fmt.Sprintf("%.2s", sexa.FmtAngle(eqTo.Dec))
if αStr != tc.α {
t.Fatal("got:", αStr, "want:", tc.α)
}
if δStr != tc.δ {
t.Fatal(δStr)
}
}
}
// test example epochs on p. 133 that are not constants in meeus/julian.go
func TestEpoch(t *testing.T) {
if math.Abs(base.BesselianYearToJDE(1950)-2433282.4235) > 1e-4 {
t.Fatal("B1950")
}
if math.Abs((base.JulianYearToJDE(2050)-2469807.5)/2469807.5) > 1e-15 {
t.Fatal("J2050")
}
}
func ExampleEclipticPrecessor_ReduceElements() {
// Example 24.a, p. 160.
ele := &elementequinox.Elements{
Inc: 47.122 * math.Pi / 180,
Peri: 151.4486 * math.Pi / 180,
Node: 45.7481 * math.Pi / 180,
}
JFrom := base.JDEToJulianYear(base.BesselianYearToJDE(1744))
JTo := base.JDEToJulianYear(base.BesselianYearToJDE(1950))
p := precess.NewEclipticPrecessor(JFrom, JTo)
p.ReduceElements(ele, ele)
fmt.Printf("i = %.4f\n", ele.Inc*180/math.Pi)
fmt.Printf("Ω = %.4f\n", ele.Node*180/math.Pi)
fmt.Printf("ω = %.4f\n", ele.Peri*180/math.Pi)
// Output:
// i = 47.1380
// Ω = 48.6037
// ω = 151.4782
}
func ExampleEclipticPrecessor_ReduceElements() {
// Example 24.a, p. 160.
ele := &elementequinox.Elements{
Inc: unit.AngleFromDeg(47.122),
Peri: unit.AngleFromDeg(151.4486),
Node: unit.AngleFromDeg(45.7481),
}
JFrom := base.JDEToJulianYear(base.BesselianYearToJDE(1744))
JTo := base.JDEToJulianYear(base.BesselianYearToJDE(1950))
p := precess.NewEclipticPrecessor(JFrom, JTo)
p.ReduceElements(ele, ele)
fmt.Printf("i = %.4f\n", ele.Inc.Deg())
fmt.Printf("Ω = %.4f\n", ele.Node.Deg())
fmt.Printf("ω = %.4f\n", ele.Peri.Deg())
// Output:
// i = 47.1380
// Ω = 48.6037
// ω = 151.4782
}