Re-packaged

julia/src/conversions.jl

@@ -0,0 +1,70 @@
+export oe_to_rθh, rθh_to_xyz, oe_to_xyz, xyz_to_oe
+
+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
+  cΩ,sΩ,ci,si,cθ,sθ = cos(Ω),sin(Ω),cos(i),sin(i),cos(θ),sin(θ)
+  DCM = [cΩ*cθ-sΩ*ci*sθ -cΩ*sθ-sΩ*ci*cθ sΩ*si;
+  sΩ*cθ+cΩ*ci*sθ -sΩ*sθ+cΩ*ci*cθ -cΩ*si;
+  si*sθ si*cθ 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