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thesis/julia/conversions.jl

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function oe_to_rθh(oe::Vector,μ::Real) :: Vector
a,e,i,Ω,ω,ν = oe
return [a*(1-e^2)/(1+e*cos(ν)),
0,
0,
(μ/sqrt(μ*a*(1-e^2)))*e*sin(ν),
(μ/sqrt(μ*a*(1-e^2)))*(1+e*cos(ν)),
0]
end
function rθh_to_xyz(rθh_vec::Vector,oe::Vector)
a,e,i,Ω,ω,ν = oe
θ = ω+ν
,,ci,si,, = cos(Ω),sin(Ω),cos(i),sin(i),cos(θ),sin(θ)
DCM = [*-*ci* -*-*ci* *si;
*+*ci* -*+*ci* -*si;
si* si* ci]
DCM = kron(Matrix(I,2,2),DCM)
return DCM*rθh_vec
end
function oe_to_xyz(oe::Vector,μ::Real)
return rθh_to_xyz(oe_to_rθh(oe,μ),oe)
end
function xyz_to_oe(cart_vec::Vector,μ::Real)
r_xyz, v_xyz = cart_vec[1:3],cart_vec[4:6]
r = norm(r_xyz)
h_xyz = cross(r_xyz,v_xyz) #km^2/s
h = norm(h_xyz) #km^2/s
ξ = dot(v_xyz,v_xyz)/2 - μ/r #km^2 s^-2
a = -μ/(2ξ) #km
e_xyz = cross(v_xyz,h_xyz)/μ - r_xyz/r
e = norm(e_xyz)
if h_xyz[3]/h < 1.
i = acos(h_xyz[3]/h) #rad
else
i = acos(1.)
end
n_xyz = cross([0,0,1],h_xyz)
if dot(n_xyz,[1,0,0])/norm(n_xyz) < 1.
Ω = acos(dot(n_xyz,[1,0,0])/norm(n_xyz))
else
Ω = acos(1.)
end
if dot(n_xyz,e_xyz)/(norm(n_xyz)*e) < 1.
ω = acos(dot(n_xyz,e_xyz)/(norm(n_xyz)*e))
else
ω = acos(1.)
end
if abs((dot(r_xyz,e_xyz))/(r*norm(e_xyz))) < 1.
ν = acos((dot(r_xyz,e_xyz))/(r*norm(e_xyz)))
else
ν = acos(1.)
end
Ω = dot(n_xyz,[0,1,0]) > 0. ? Ω : -Ω
ω = dot(e_xyz,[0,0,1]) > 0. ? ω : -ω
ν = dot(r_xyz,v_xyz) > 0. ? ν : -ν
return [a,e,i,Ω,ω,ν]
end