🔧 Improve simultaneously init and prop

Our tests indicate that we have no need to define custom functions to
simultaneously initialize and propagate. We can use the API functions
with virtually no penalty.

src/API.md

@@ -180,18 +180,6 @@ Propagators.name(orbp)
 to return its name. The system uses this information to display the object using the
 function `show`. If the function is not provided, the structure name is used by default.
 
-### Simultaneous Initialization and Propagation (Optional)
-
-If the propagator supports, it can overload the functions:
-
-```julia
-Propagators.propagate(t, args...; kwargs...)
-```
-
-that simultaneously initialize and propagate the orbit to the instant `t` [s] after the
-input elements. `args...` and `kwargs...` must be the same as in the initialization function
-`Propagators.init`.
-
 ### Fitting Mean Elements (Optional)
 
 The propagator can implement the following functions to fit a set of osculating state

src/api/Propagators.jl

@@ -111,21 +111,29 @@ structure name is used: `typeof(orbp) |> string`.
 name(orbp::OrbitPropagator) = typeof(orbp) |> string
 
 """
-    propagate(::Val{:propagator}, Δt::Number, args...; kwargs...)
+    propagate(::Val{:propagator}, Δt::Number, args...; kwargs...) -> SVector{3, T}, SVector{3, T}, OrbitPropagator
 
 Initialize the orbit `propagator` and propagate the orbit by `t` [s] from the initial orbit
 epoch. The initialization arguments `args...` and `kwargs...` are the same as in the
 initialization function [`Propagators.init`](@ref).
 
+!!! note
+
+    `T` is the propagator number type. For more information, see [`Propagators.init`](@ref).
+
 # Returns
 
 - `SVector{3, T}`: Position vector [m] represented in the inertial frame at propagation
     instant.
 - `SVector{3, T}`: Velocity vector [m / s] represented in the inertial frame at propagation
     instant.
-- [`OrbitPropagator`](@ref): Structure with the initialized parameters.
+- [`OrbitPropagator{Tepoch, T}`](@ref): Structure with the initialized propagator.
 """
-function propagate end
+function propagate(prop, Δt::Number, args...; kwargs...)
+    orbp = Propagators.init(prop, args...; kwargs...)
+    r_i, v_i = Propagators.propagate!(orbp, Δt)
+    return r_i, v_i, orbp
+end
 
 """
     propagate!(orbp::OrbitPropagator{Tepoch, T}, t::Number) where {Tepoch, T} -> SVector{3, T}, SVector{3, T}

src/api/j2.jl

@@ -171,40 +171,6 @@ function Propagators.init!(orbp::OrbitPropagatorJ2, orb₀::KeplerianElements)
     return nothing
 end
 
-"""
-    Propagators.propagate(Val(:J2), Δt::Number, orb₀::KeplerianElements; kwargs...) -> SVector{3, T}, SVector{3, T}, OrbitPropagatorJ2
-
-Initialize the J2 propagator structure using the input elements `orb₀` [SI units] and
-propagate the orbit until the time Δt [s].
-
-!!! note
-
-    The type used in the propagation will be the same as used to define the constants in the
-    structure `j2c`.
-
-# Keywords
-
-- `j2c::J2PropagatorConstants{T}`: J2 orbit propagator constants (see
-  [`J2PropagatorConstants`](@ref)). (**Default** = `j2c_egm2008`)
-
-# Returns
-
-- `SVector{3, T}`: Position vector [m] represented in the inertial frame at propagation
-    instant.
-- `SVector{3, T}`: Velocity vector [m / s] represented in the inertial frame at propagation
-    instant.
-- [`OrbitPropagatorJ2`](@ref): Structure with the initialized parameters.
-"""
-function Propagators.propagate(
-    ::Val{:J2},
-    Δt::Number,
-    orb₀::KeplerianElements;
-    j2c::J2PropagatorConstants = j2c_egm2008
-)
-    r_i, v_i, j2d = j2(Δt, orb₀; j2c = j2c)
-    return r_i, v_i, OrbitPropagatorJ2(j2d)
-end
-
 function Propagators.propagate!(orbp::OrbitPropagatorJ2, t::Number)
     # Auxiliary variables.
     j2d = orbp.j2d

src/api/j2osc.jl

@@ -171,40 +171,6 @@ function Propagators.init!(orbp::OrbitPropagatorJ2Osculating, orb₀::KeplerianE
     return nothing
 end
 
-"""
-    Propagators.propagate(Val(:J2osc), Δt::Number, orb₀::KeplerianElements; kwargs...) -> SVector{3, T}, SVector{3, T}, OrbitPropagatorJ2Osculating
-
-Initialize the J2 osculating propagator structure using the input elements `orb₀` [SI units]
-and propagate the orbit until the time Δt [s].
-
-!!! note
-
-    The type used in the propagation will be the same as used to define the constants in the
-    structure `j2c`.
-
-# Keywords
-
-- `j2c::J2PropagatorConstants{T}`: J2 orbit propagator constants (see
-  [`J2PropagatorConstants`](@ref)). (**Default** = `j2c_egm2008`)
-
-# Returns
-
-- `SVector{3, T}`: Position vector [m] represented in the inertial frame at propagation
-    instant.
-- `SVector{3, T}`: Velocity vector [m / s] represented in the inertial frame at propagation
-    instant.
-- [`OrbitPropagatorJ2Osculating`](@ref): Structure with the initialized parameters.
-"""
-function Propagators.propagate(
-    ::Val{:J2osc},
-    Δt::Number,
-    orb₀::KeplerianElements;
-    j2c::J2PropagatorConstants = j2c_egm2008
-)
-    r_i, v_i, j2oscd = j2osc(Δt, orb₀; j2c = j2c)
-    return r_i, v_i, OrbitPropagatorJ2Osculating(j2oscd)
-end
-
 function Propagators.propagate!(orbp::OrbitPropagatorJ2Osculating, t::Number)
     # Auxiliary variables.
     j2oscd = orbp.j2oscd

src/api/j4.jl

@@ -172,41 +172,6 @@ function Propagators.init!(orbp::OrbitPropagatorJ4, orb₀::KeplerianElements)
     return nothing
 end
 
-"""
-    Propagators.propagate(Val(:J4), Δt::Number, orb₀::KeplerianElements; kwargs...) -> SVector{3, T}, SVector{3, T}, OrbitPropagatorJ4
-
-Initialize the J4 propagator structure using the input elements `orb₀` and propagate the
-orbit until the time Δt [s].
-
-!!! note
-
-    The type used in the propagation will be the same as used to define the constants in the
-    structure `j4c`.
-
-# Keywords
-
-- `j4c::J4PropagatorConstants{T}`: J4 orbit propagator constants (see
-    [`J4PropagatorConstants`](@ref)).
-    (**Default** = `j4c_egm2008`)
-
-# Returns
-
-- `SVector{3, T}`: Position vector [m] represented in the inertial frame at propagation
-    instant.
-- `SVector{3, T}`: Velocity vector [m / s] represented in the inertial frame at propagation
-    instant.
-- [`OrbitPropagatorJ4`](@ref): Structure with the initialized parameters.
-"""
-function Propagators.propagate(
-    ::Val{:J4},
-    Δt::Number,
-    orb₀::KeplerianElements;
-    j4c::J4PropagatorConstants = j4c_egm2008
-)
-    r_i, v_i, j4d = j4(Δt, orb₀; j4c = j4c)
-    return r_i, v_i, OrbitPropagatorJ4(j4d)
-end
-
 function Propagators.propagate!(orbp::OrbitPropagatorJ4, t::Number)
     # Auxiliary variables.
     j4d = orbp.j4d

src/api/j4osc.jl

@@ -174,41 +174,6 @@ function Propagators.init!(orbp::OrbitPropagatorJ4Osculating, orb₀::KeplerianE
     return nothing
 end
 
-"""
-    Propagators.propagate(Val(:J4osc), Δt::Number, orb₀::KeplerianElements; kwargs...) -> SVector{3, T}, SVector{3, T}, OrbitPropagatorJ4Osculating
-
-Initialize the J4 osculating propagator structure using the input elements `orb₀` and
-propagate the orbit until the time Δt [s].
-
-!!! note
-
-    The type used in the propagation will be the same as used to define the constants in the
-    structure `j4c`.
-
-# Keywords
-
-- `j4c::J4PropagatorConstants{T}`: J4 orbit propagator constants (see
-    [`J4PropagatorConstants`](@ref)).
-    (**Default** = `j4c_egm2008`)
-
-# Returns
-
-- `SVector{3, T}`: Position vector [m] represented in the inertial frame at propagation
-    instant.
-- `SVector{3, T}`: Velocity vector [m / s] represented in the inertial frame at propagation
-    instant.
-- [`OrbitPropagatorJ4Osculating`](@ref): Structure with the initialized parameters.
-"""
-function Propagators.propagate(
-    ::Val{:J4osc},
-    Δt::Number,
-    orb₀::KeplerianElements;
-    j4c::J4PropagatorConstants = j4c_egm2008
-)
-    r_i, v_i, j4oscd = j4osc(Δt, orb₀; j4c = j4c)
-    return r_i, v_i, OrbitPropagatorJ4Osculating(j4oscd)
-end
-
 function Propagators.propagate!(orbp::OrbitPropagatorJ4Osculating, t::Number)
     # Auxiliary variables.
     j4oscd = orbp.j4oscd

src/api/sgp4.jl

@@ -377,81 +377,6 @@ function Propagators.init!(
     return nothing
 end
 
-"""
-    Propagators.propagate(Val(:SGP4), Δt::Number, epoch::Number, n₀::Number, e₀::Number, i₀::Number, Ω₀::Number, ω₀::Number, M₀::Number, bstar::Number; kwargs...)
-    Propagators.propagate(Val(:SGP4), Δt::Number, tle::TLE; kwargs...)
-
-Initialize the SGP4 propagator structure using the input arguments and propagate the orbit
-until the time Δt [s].
-
-!!! note
-
-    The type used in the propagation will be the same as used to define the constants in the
-    structure `sgp4c`.
-
-# Arguments
-
-- `epoch::Number`: Epoch of the orbital elements [Julian Day].
-- `n₀::Number`: SGP type "mean" mean motion at epoch [rad/s].
-- `e₀::Number`: "Mean" eccentricity at epoch.
-- `i₀::Number`: "Mean" inclination at epoch [rad].
-- `Ω₀::Number`: "Mean" longitude of the ascending node at epoch [rad].
-- `ω₀::Number`: "Mean" argument of perigee at epoch [rad].
-- `M₀::Number`: "Mean" mean anomaly at epoch [rad].
-- `bstar::Number`: Drag parameter (B*).
-- `tle::TLE`: Two-line elements used for the initialization.
-
-# Keywords
-
-- `sgp4c::Sgp4Constants{T}`: SGP4 orbit propagator constants (see `Sgp4Constants`).
-    (**Default** = `sgp4c_wgs84`)
-
-# Returns
-
-- `SVector{3, T}`: Position vector [m] represented in the inertial frame at propagation
-    instant.
-- `SVector{3, T}`: Velocity vector [m / s] represented in the inertial frame at propagation
-    instant.
-- [`OrbitPropagatorSgp4`](@ref): Structure with the initialized parameters.
-"""
-function Propagators.propagate(
-    ::Val{:SGP4},
-    Δt::Number,
-    tle::TLE;
-    sgp4c::Sgp4Constants = sgp4c_wgs84
-)
-    r_i, v_i, sgp4d = sgp4(Δt / 60, tle; sgp4c = sgp4c)
-    return 1000r_i, 1000v_i, OrbitPropagatorSgp4(sgp4d)
-end
-
-function Propagators.propagate(
-    ::Val{:SGP4},
-    Δt::Number,
-    epoch::Number,
-    n₀::Number,
-    e₀::Number,
-    i₀::Number,
-    Ω₀::Number,
-    ω₀::Number,
-    M₀::Number,
-    bstar::Number;
-    sgp4c::Sgp4Constants = sgp4c_wgs84
-)
-    r_i, v_i, sgp4d = sgp4(
-        Δt / 60,
-        epoch,
-        60n₀,
-        e₀,
-        i₀,
-        Ω₀,
-        ω₀,
-        M₀,
-        bstar;
-        sgp4c = sgp4c
-    )
-    return 1000r_i, 1000v_i, OrbitPropagatorSgp4(sgp4d)
-end
-
 function Propagators.propagate!(orbp::OrbitPropagatorSgp4, t::Number)
     # Auxiliary variables.
     sgp4d = orbp.sgp4d

src/api/twobody.jl

@@ -50,40 +50,6 @@ function Propagators.init!(orbp::OrbitPropagatorTwoBody, orb₀::KeplerianElemen
     return nothing
 end
 
-"""
-    Propagators.propagate(Val(:TwoBody), Δt::Number, orb₀::KeplerianElements; kwargs...) -> SVector{3, T}, SVector{3, T}, OrbitPropagatorTwoBody
-
-Initialize the two-body propagator structure using the input elements `orb₀` and propagate
-the orbit until the time Δt [s].
-
-!!! note
-
-    The type used in the propagation will be the same as used to define the gravitational
-    constant `m0`.
-
-# Keywords
-
-- `m0::T`: Standard gravitational parameter of the central body [m³ / s²].
-    (**Default** = `tbc_m0`)
-
-# Returns
-
-- `SVector{3, T}`: Position vector [m] represented in the inertial frame at propagation
-    instant.
-- `SVector{3, T}`: Velocity vector [m / s] represented in the inertial frame at propagation
-    instant.
-- [`OrbitPropagatorTwoBody`](@ref): Structure with the initialized parameters.
-"""
-function Propagators.propagate(
-    ::Val{:TwoBody},
-    Δt::Number,
-    orb₀::KeplerianElements;
-    m0::Number = tbc_m0
-)
-    r_i, v_i, tbd = twobody(Δt, orb₀; m0 = m0)
-    return r_i, v_i, OrbitPropagatorTwoBody(tbd)
-end
-
 function Propagators.propagate!(orbp::OrbitPropagatorTwoBody, t::Number)
     # Auxiliary variables.
     tbd = orbp.tbd