Dynamics

Index

Warning

In the examples in the documentation below, the methods are not prefixed by the module name even if they are private.

julia> using CTModels
julia> x = 1
julia> private_fun(x) # throw an error

must be replaced by

julia> using CTModels
julia> x = 1
julia> CTModels.private_fun(x)

However, if the method is reexported by another package, then, there is no need of prefixing.

julia> module OptimalControl
           import CTModels: private_fun
           export private_fun
       end
julia> using OptimalControl
julia> x = 1
julia> private_fun(x)

Documentation

CTModels.__build_dynamics_from_parts — Method

__build_dynamics_from_parts(
    parts::Vector{<:Tuple{var"#s53", var"#s52"} where {var"#s53"<:(AbstractRange{<:Int64}), var"#s52"<:Function}}
) -> CTModels.var"#dyn!#64"{Vector{var"#s54"}} where var"#s54"<:(Tuple{var"#s53", var"#s52"} where {var"#s53"<:(AbstractRange{<:Int64}), var"#s52"<:Function})

Build a combined dynamics function from multiple parts.

This function constructs an in-place dynamics function dyn! by composing several sub-functions, each responsible for updating a specific segment of the output vector.

Arguments

parts::Vector{<:Tuple{<:AbstractRange{<:Int}, <:Function}}: A vector of tuples, where each tuple contains:
- A range specifying the indices in the output vector val that the corresponding function updates.
- A function f with the signature (output_segment, t, x, u, v), which updates the slice of val indicated by the range.

Returns

dyn!: A function with signature (val, t, x, u, v) that updates the full output vector val in-place by applying each part function to its assigned segment.

Details

The returned dyn! function calls each part function with a view of val restricted to the assigned range. This avoids unnecessary copying and allows efficient updates of sub-vectors.
Each part function is expected to modify its output segment in-place.

Example

# Define two sub-dynamics functions
julia> f1(out, t, x, u, v) = out .= x[1:2] .+ u[1:2]
julia> f2(out, t, x, u, v) = out .= x[3] * v

# Combine them into one dynamics function affecting different parts of the output vector
julia> parts = [(1:2, f1), (3:3, f2)]
julia> dyn! = __build_dynamics_from_parts(parts)

val = zeros(3)
julia> dyn!(val, 0.0, [1.0, 2.0, 3.0], [0.5, 0.5], 2.0)
julia> println(val)  # prints [1.5, 2.5, 6.0]

CTModels.dynamics! — Method

dynamics!(
    ocp::CTModels.PreModel,
    rg::AbstractRange{<:Int64},
    f::Function
)

Add a partial dynamics function f to the optimal control problem ocp, applying to the subset of state indices specified by the range rg.

Arguments

ocp::PreModel: The optimal control problem being defined.
rg::AbstractRange{<:Int}: Range of state indices to which f applies.
f::Function: A function describing the dynamics over the specified state indices.

Preconditions

The state, control, and times must be set before calling this function.
The full dynamics must not yet be complete.
No overlap is allowed between rg and existing dynamics index ranges.

Behavior

This function appends the tuple (rg, f) to the list of partial dynamics. It ensures that the specified indices are not already covered and that the system is in a valid configuration for adding partial dynamics.

Errors

Throws CTBase.UnauthorizedCall if:

The state, control, or times are not yet set.
The dynamics are already defined completely.
Any index in rg overlaps with an existing dynamics range.

Example

julia> dynamics!(ocp, 1:2, (out, t, x, u, v) -> out .= x[1:2] .+ u[1:2])
julia> dynamics!(ocp, 3:3, (out, t, x, u, v) -> out .= x[3] * v[1])

CTModels.dynamics! — Method

dynamics!(ocp::CTModels.PreModel, f::Function)

Set the full dynamics of the optimal control problem ocp using the function f.

Arguments

ocp::PreModel: The optimal control problem being defined.
f::Function: A function that defines the complete system dynamics.

Preconditions

The state, control, and times must be set before calling this function.
No dynamics must have been set previously.

Behavior

This function assigns f as the complete dynamics of the system. It throws an error if any of the required fields (state, control, times) are not yet set, or if dynamics have already been set.

Errors

Throws CTBase.UnauthorizedCall if called out of order or in an invalid state.

CTModels.dynamics! — Method

dynamics!(ocp::CTModels.PreModel, i::Integer, f::Function)

Define partial dynamics for a single state variable index in an optimal control problem.

This is a convenience method for defining dynamics affecting only one element of the state vector. It wraps the scalar index i into a range i:i and delegates to the general partial dynamics method.

Arguments

ocp::PreModel: The optimal control problem being defined.
i::Integer: The index of the state variable to which the function f applies.
f::Function: A function of the form (out, t, x, u, v) -> ..., which updates the scalar output out[1] in-place.

Behavior

This is equivalent to calling:

julia> dynamics!(ocp, i:i, f)

Errors

Throws the same errors as the range-based method if:

The model is not properly initialized.
The index i overlaps with existing dynamics.
A full dynamics function is already defined.

Example

julia> dynamics!(ocp, 3, (out, t, x, u, v) -> out[1] = x[3]^2 + u[1])