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Orbital elements: Difference between revisions
Add Swift
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Speed : Vector(-1.06193301748006004757467368094494935655538772696, 0.275850020569249507846452830330085489348356659642, 0.135747024865598167166145512759280712986072818844)
</pre>
=={{header|Swift}}==
{{trans|Kotlin}}
<lang swift>import Foundation
public struct Vector {
public var x = 0.0
public var y = 0.0
public var z = 0.0
public init(x: Double, y: Double, z: Double) {
(self.x, self.y, self.z) = (x, y, z)
}
public func mod() -> Double {
(x * x + y * y + z * z).squareRoot()
}
public static func + (lhs: Vector, rhs: Vector) -> Vector {
return Vector(
x: lhs.x + rhs.x,
y: lhs.y + rhs.y,
z: lhs.z + rhs.z
)
}
public static func * (lhs: Vector, rhs: Double) -> Vector {
return Vector(
x: lhs.x * rhs,
y: lhs.y * rhs,
z: lhs.z * rhs
)
}
public static func *= (lhs: inout Vector, rhs: Double) {
lhs.x *= rhs
lhs.y *= rhs
lhs.z *= rhs
}
public static func / (lhs: Vector, rhs: Double) -> Vector {
return lhs * (1 / rhs)
}
public static func /= (lhs: inout Vector, rhs: Double) {
lhs = lhs * (1 / rhs)
}
}
extension Vector: CustomStringConvertible {
public var description: String {
return String(format: "%.6f\t%.6f\t%.6f", x, y, z)
}
}
private func mulAdd(v1: Vector, x1: Double, v2: Vector, x2: Double) -> Vector {
return v1 * x1 + v2 * x2
}
private func rotate(_ i: Vector, _ j: Vector, alpha: Double) -> (Vector, Vector) {
return (
mulAdd(v1: i, x1: +cos(alpha), v2: j, x2: sin(alpha)),
mulAdd(v1: i, x1: -sin(alpha), v2: j, x2: cos(alpha))
)
}
public func orbitalStateVectors(
semimajorAxis: Double,
eccentricity: Double,
inclination: Double,
longitudeOfAscendingNode: Double,
argumentOfPeriapsis: Double,
trueAnomaly: Double
) -> (Vector, Vector) {
var i = Vector(x: 1.0, y: 0.0, z: 0.0)
var j = Vector(x: 0.0, y: 1.0, z: 0.0)
let k = Vector(x: 0.0, y: 0.0, z: 1.0)
(i, j) = rotate(i, j, alpha: longitudeOfAscendingNode)
(j, _) = rotate(j, k, alpha: inclination)
(i, j) = rotate(i, j, alpha: argumentOfPeriapsis)
let l = eccentricity == 1.0 ? 2.0 : 1.0 - eccentricity * eccentricity
let c = cos(trueAnomaly)
let s = sin(trueAnomaly)
let r = l / (1.0 + eccentricity * c)
let rPrime = s * r * r / l
let position = mulAdd(v1: i, x1: c, v2: j, x2: s) * r
var speed = mulAdd(v1: i, x1: rPrime * c - r * s, v2: j, x2: rPrime * s + r * c)
speed /= speed.mod()
speed *= (2.0 / r - 1.0 / semimajorAxis).squareRoot()
return (position, speed)
}
let (position, speed) = orbitalStateVectors(
semimajorAxis: 1.0,
eccentricity: 0.1,
inclination: 0.0,
longitudeOfAscendingNode: 355.0 / (113.0 * 6.0),
argumentOfPeriapsis: 0.0,
trueAnomaly: 0.0
)
print("Position: \(position); Speed: \(speed)")</lang>
{{out}}
<pre>Position: 0.779423 0.450000 0.000000; Speed: -0.552771 0.957427 0.000000</pre>
=={{header|zkl}}==
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