Orbital elements: Difference between revisions

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 {{out}}
 <pre>{position => 0.237771283982207*e0+0.860960261697716*e1+0.110509023572076*e2, speed => -1.06193301748006*e0+0.27585002056925*e1+0.135747024865598*e2}</pre>
+=={{header|Sidef}}==
+{{trans|Perl}}
+<lang ruby>func orbital_state_vectors(
+    semimajor_axis,
+    eccentricity,
+    inclination,
+    longitude_of_ascending_node,
+    argument_of_periapsis,
+    true_anomaly
+) {
+    var (i, j, k) = (vec.V(1,0,0), vec.V(0,1,0), vec.V(0,0,1))
+    func muladd(v1, x1, v2, x2) {
+        v1.mul(x1).add(v2.mul(x2))
+    }
+    func rotate(Ref i, Ref j, α) {
+        (*i, *j) = (
+            muladd(*i, +cos(α), *j, sin(α)),
+            muladd(*i, -sin(α), *j, cos(α)),
+        )
+    }
+    rotate(\i, \j, longitude_of_ascending_node)
+    rotate(\j, \k, inclination)
+    rotate(\i, \j, argument_of_periapsis)
+    var l = (eccentricity == 1 ? 2*semimajor_axis
+                               : semimajor_axis*(1 - eccentricity**2))
+    var (c, s) = given(true_anomaly) { (.cos, .sin) }
+    var r = l/(1 + eccentricity*c)
+    var rprime = (s * r**2 / l)
+    var position = muladd(i, c, j, s).mul(r)
+    var speed = muladd(i, rprime*c - r*s, j, rprime*s + r*c)
+    speed.div!(abs(speed))
+    speed.mul!(sqrt(2/r - 1/semimajor_axis))
+    struct Result { position, speed }
+    Result([position,speed].map {|v| [v{:module}[]] }...)
+}
+var r = orbital_state_vectors(
+    semimajor_axis: 1,
+    eccentricity: 0.1,
+    inclination: 0,
+    longitude_of_ascending_node: 355/(113*6),
+    argument_of_periapsis: 0,
+    true_anomaly: 0,
+)
+say r.position
+say r.speed</lang>
+{{out}}
+<pre>
+[0.77942284339868, 0.450000034653684, 0]
+[-0.552770840960444, 0.957427083179761, 0]
+</pre>
 =={{header|zkl}}==