Orbital elements: Difference between revisions
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Position : (0.77942284339868, 0.45000003465368, 0)
Speed : (-0.55277084096044, 0.95742708317976, 0)
</pre>
=={{header|XPL0}}==
{{trans|C}}
<syntaxhighlight lang "XPL0">include xpllib; \for VCopy, VAdd, VMul, VDiv, VMag and Print
proc VShow(A);
real A;
Print("(%1.6f, %1.6f, %1.6f)\n", A(0), A(1), A(2));
func real VMulAdd(V0, V1, V2, X1, X2);
real V0, V1, V2, X1, X2, V3(3), V4(3);
return VAdd(V0, VMul(V3, V1, X1), VMul(V4, V2, X2));
proc Rotate(I, J, Alpha, PS);
real I, J, Alpha, PS;
[VMulAdd(PS(0), I, J, Cos(Alpha), Sin(Alpha));
VMulAdd(PS(1), I, J, -Sin(Alpha), Cos(Alpha));
];
proc OrbitalStateVectors; real SemiMajorAxis, Eccentricity, Inclination,
LongitudeOfAscendingNode, ArgumentOfPeriapsis, TrueAnomaly, PS;
real I, J, K, L, QS(2,3), C, S, R, RPrime;
[I:= [1.0, 0.0, 0.0];
J:= [0.0, 1.0, 0.0];
K:= [0.0, 0.0, 1.0];
L:= 2.0;
Rotate(I, J, LongitudeOfAscendingNode, QS);
VCopy(I, QS(0)); VCopy(J, QS(1));
Rotate(J, K, Inclination, QS);
VCopy(J, QS(0));
Rotate(I, J, ArgumentOfPeriapsis, QS);
VCopy(I, QS(0)); VCopy(J, QS(1));
if Eccentricity # 1.0 then L:= 1.0 - Eccentricity*Eccentricity;
L:= L * SemiMajorAxis;
C:= Cos(TrueAnomaly);
S:= Sin(TrueAnomaly);
R:= L / (1.0 + Eccentricity*C);
RPrime:= S * R * R / L;
VMulAdd(PS(0), I, J, C, S);
VMul(PS(0), PS(0), R);
VMulAdd(PS(1), I, J, RPrime*C - R*S, RPrime*S + R*C);
VDiv(PS(1), PS(1), VMag(PS(1)));
VMul(PS(1), PS(1), sqrt(2.0/R - 1.0/SemiMajorAxis));
];
def Longitude = 355.0 / (113.0 * 6.0);
real PS(2,3);
[OrbitalStateVectors(1.0, 0.1, 0.0, Longitude, 0.0, 0.0, PS);
Print("Position : "); VShow(PS(0));
Print("Speed : "); VShow(PS(1));
]</syntaxhighlight>
{{out}}
<pre>
Position : (0.779423, 0.450000, 0.000000)
Speed : (-0.552771, 0.957427, 0.000000)
</pre>
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