Golang base.NewAngle函数代码示例

func TestPrecessor_Precess(t *testing.T) {
	// Exercise, p. 136.
	eqFrom := &coord.Equatorial{
		RA:  base.NewRA(2, 31, 48.704).Rad(),
		Dec: base.NewAngle(false, 89, 15, 50.72).Rad(),
	}
	mα := base.NewHourAngle(false, 0, 0, .19877)
	mδ := base.NewAngle(false, 0, 0, -.0152)
	epochs := []float64{
		base.JDEToJulianYear(base.B1900),
		2050,
		2100,
	}
	answer := []string{
		"α = 1ʰ22ᵐ33ˢ.90   δ = +88°46′26″.18",
		"α = 3ʰ48ᵐ16ˢ.43   δ = +89°27′15″.38",
		"α = 5ʰ53ᵐ29ˢ.17   δ = +89°32′22″.18",
	}
	eqTo := &coord.Equatorial{}
	for i, epochTo := range epochs {
		precess.Position(eqFrom, eqTo, 2000, epochTo, mα, mδ)
		if answer[i] != fmt.Sprintf("α = %0.2d   δ = %+0.2d",
			base.NewFmtRA(eqTo.RA), base.NewFmtAngle(eqTo.Dec)) {
			t.Fatal(i)
		}
	}
}

func ExampleProperMotion3D() {
	// Example 21.d, p. 141.
	eqFrom := &coord.Equatorial{
		RA:  base.NewRA(6, 45, 8.871).Rad(),
		Dec: base.NewAngle(true, 16, 42, 57.99).Rad(),
	}
	mra := base.NewHourAngle(false, 0, 0, -0.03847)
	mdec := base.NewAngle(false, 0, 0, -1.2053)
	r := 2.64           // given in correct unit
	mr := -7.6 / 977792 // magic conversion factor
	eqTo := &coord.Equatorial{}
	fmt.Printf("Δr = %.9f, Δα = %.10f, Δδ = %.10f\n", mr, mra, mdec)
	for _, epoch := range []float64{1000, 0, -1000, -2000, -10000} {
		precess.ProperMotion3D(eqFrom, eqTo, 2000, epoch, r, mr, mra, mdec)
		fmt.Printf("%8.1f  %0.2d  %-0.1d\n", epoch,
			base.NewFmtRA(eqTo.RA), base.NewFmtAngle(eqTo.Dec))
	}
	// Output:
	// Δr = -0.000007773, Δα = -0.0000027976, Δδ = -0.0000058435
	//   1000.0  6ʰ45ᵐ47ˢ.16  -16°22′56″.0
	//      0.0  6ʰ46ᵐ25ˢ.09  -16°03′00″.8
	//  -1000.0  6ʰ47ᵐ02ˢ.67  -15°43′12″.3
	//  -2000.0  6ʰ47ᵐ39ˢ.91  -15°23′30″.6
	// -10000.0  6ʰ52ᵐ25ˢ.72  -12°50′06″.7
}

// 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)
		}
	}
}

func ExampleApproxTimes() {
	// Example 15.a, p. 103.
	jd := julian.CalendarGregorianToJD(1988, 3, 20)
	p := globe.Coord{
		Lon: base.NewAngle(false, 71, 5, 0).Rad(),
		Lat: base.NewAngle(false, 42, 20, 0).Rad(),
	}
	// Meeus gives us the value of 11h 50m 58.1s but we have a package
	// function for this:
	Th0 := sidereal.Apparent0UT(jd)
	α := base.NewRA(2, 46, 55.51).Rad()
	δ := base.NewAngle(false, 18, 26, 27.3).Rad()
	h0 := rise.Stdh0Stellar
	rise, transit, set, err := rise.ApproxTimes(p, h0, Th0, α, δ)
	if err != nil {
		fmt.Println(err)
		return
	}
	// Units for approximate values given near top of p. 104 are circles.
	fmt.Printf("rising:  %+.5f\n", rise/86400)
	fmt.Printf("transit: %+.5f\n", transit/86400)
	fmt.Printf("seting:  %+.5f\n", set/86400)
	// Output:
	// rising:  +0.51816
	// transit: +0.81965
	// seting:  +0.12113
}

func ExampleNewAngle() {
	// Example negative values, p. 9.
	a := base.NewAngle(true, 13, 47, 22)
	fmt.Println(base.NewFmtAngle(a.Rad()))
	a = base.NewAngle(true, 0, 32, 41)
	// use # flag to force output of all three components
	fmt.Printf("%#s\n", base.NewFmtAngle(a.Rad()))
	// Output:
	// -13°47′22″
	// -0°32′41″
}

// First exercise, p. 110.
func TestSep(t *testing.T) {
	r1 := base.NewRA(4, 35, 55.2).Rad()
	d1 := base.NewAngle(false, 16, 30, 33).Rad()
	r2 := base.NewRA(16, 29, 24).Rad()
	d2 := base.NewAngle(true, 26, 25, 55).Rad()
	d := angle.Sep(r1, d1, r2, d2)
	answer := base.NewAngle(false, 169, 58, 0).Rad()
	if math.Abs(d-answer) > 1e-4 {
		t.Fatal(base.NewFmtAngle(d))
	}
}

func ExampleSep() {
	// Example 17.a, p. 110.
	r1 := base.NewRA(14, 15, 39.7).Rad()
	d1 := base.NewAngle(false, 19, 10, 57).Rad()
	r2 := base.NewRA(13, 25, 11.6).Rad()
	d2 := base.NewAngle(true, 11, 9, 41).Rad()
	d := angle.Sep(r1, d1, r2, d2)
	fmt.Println(base.NewFmtAngle(d))
	// Output:
	// 32°47′35″
}

func TestSepHav(t *testing.T) {
	// Example 17.a, p. 110.
	r1 := base.NewRA(14, 15, 39.7).Rad()
	d1 := base.NewAngle(false, 19, 10, 57).Rad()
	r2 := base.NewRA(13, 25, 11.6).Rad()
	d2 := base.NewAngle(true, 11, 9, 41).Rad()
	d := angle.SepHav(r1, d1, r2, d2)
	s := fmt.Sprint(base.NewFmtAngle(d))
	if s != "32°47′35″" {
		t.Fatal(s)
	}
}

func ExampleAngleError() {
	// Example p. 125.
	rδ := base.NewRA(5, 32, 0.40).Rad()
	dδ := base.NewAngle(true, 0, 17, 56.9).Rad()
	rε := base.NewRA(5, 36, 12.81).Rad()
	dε := base.NewAngle(true, 1, 12, 7.0).Rad()
	rζ := base.NewRA(5, 40, 45.52).Rad()
	dζ := base.NewAngle(true, 1, 56, 33.3).Rad()

	n, ω := line.AngleError(rδ, dδ, rε, dε, rζ, dζ)
	fmt.Printf("%.62s\n", base.NewFmtAngle(n))
	fmt.Println(base.NewFmtAngle(ω))
	// Output:
	// 7°31′
	// -5′24″
}

// p. 83
func TestLatDiff(t *testing.T) {
	φ0 := base.NewAngle(false, 45, 5, 46.36).Rad()
	diff := base.NewFmtAngle(globe.GeocentricLatitudeDifference(φ0))
	if f := fmt.Sprintf("%.2d", diff); f != "11′32″.73" {
		t.Fatal(f)
	}
}

func ExamplePositionRonVondrak() {
	// Example 23.b, p. 156
	jd := julian.CalendarGregorianToJD(2028, 11, 13.19)
	eq := &coord.Equatorial{
		RA:  base.NewRA(2, 44, 11.986).Rad(),
		Dec: base.NewAngle(false, 49, 13, 42.48).Rad(),
	}
	apparent.PositionRonVondrak(eq, eq, base.JDEToJulianYear(jd),
		base.NewHourAngle(false, 0, 0, 0.03425),
		base.NewAngle(true, 0, 0, 0.0895))
	fmt.Printf("α = %0.3d\n", base.NewFmtRA(eq.RA))
	fmt.Printf("δ = %0.2d\n", base.NewFmtAngle(eq.Dec))
	// Output:
	// α = 2ʰ46ᵐ14ˢ.392
	// δ = 49°21′07″.45
}

func ExampleAngle() {
	// Example p. 123.
	rδ := base.NewRA(5, 32, 0.40).Rad()
	dδ := base.NewAngle(true, 0, 17, 56.9).Rad()
	rε := base.NewRA(5, 36, 12.81).Rad()
	dε := base.NewAngle(true, 1, 12, 7.0).Rad()
	rζ := base.NewRA(5, 40, 45.52).Rad()
	dζ := base.NewAngle(true, 1, 56, 33.3).Rad()

	n := line.Angle(rδ, dδ, rε, dε, rζ, dζ)
	fmt.Printf("%.4f degrees\n", n*180/math.Pi)
	fmt.Printf("%.62s\n", base.NewFmtAngle(n))
	// Output:
	// 172.4830 degrees
	// 172°29′
}

func ExampleApproxPosition() {
	// Example 21.a, p. 132.
	eq := &coord.Equatorial{
		base.NewRA(10, 8, 22.3).Rad(),
		base.NewAngle(false, 11, 58, 2).Rad(),
	}
	epochFrom := 2000.0
	epochTo := 1978.0
	mα := base.NewHourAngle(true, 0, 0, 0.0169)
	mδ := base.NewAngle(false, 0, 0, 0.006)
	precess.ApproxPosition(eq, eq, epochFrom, epochTo, mα, mδ)
	fmt.Printf("%0.1d\n", base.NewFmtRA(eq.RA))
	fmt.Printf("%+0d\n", base.NewFmtAngle(eq.Dec))
	// Output:
	// 10ʰ07ᵐ12ˢ.1
	// +12°04′32″
}

// ApproxAnnualPrecession returns approximate annual precision in right
// ascension and declination.
//
// The two epochs should be within a few hundred years.
// The declinations should not be too close to the poles.
func ApproxAnnualPrecession(eq *coord.Equatorial, epochFrom, epochTo float64) (Δα base.HourAngle, Δδ base.Angle) {
	m, na, nd := mn(epochFrom, epochTo)
	sa, ca := math.Sincos(eq.RA)
	// (21.1) p. 132
	Δαs := m + na*sa*math.Tan(eq.Dec) // seconds of RA
	Δδs := nd * ca                    // seconds of Dec
	return base.NewHourAngle(false, 0, 0, Δαs), base.NewAngle(false, 0, 0, Δδs)
}

// MeanObliquity returns mean obliquity (ε₀) following the IAU 1980
// polynomial.
//
// Accuracy is 1″ over the range 1000 to 3000 years and 10″ over the range
// 0 to 4000 years.
//
// Result unit is radians.
func MeanObliquity(jde float64) float64 {
	// (22.2) p. 147
	return base.Horner(base.J2000Century(jde),
		base.NewAngle(false, 23, 26, 21.448).Rad(),
		-46.815/3600*(math.Pi/180),
		-0.00059/3600*(math.Pi/180),
		0.001813/3600*(math.Pi/180))
}