Variable

[ocots]

This definition is not authorized:

α = 5
@def ocp begin
    t ∈ [ 0, 1 ], time
    v ∈ R, variable
    x ∈ R², state
    u ∈ R, control
    x(0) == [ -1, 0 ]
    x(1) == [ 0, v ]
    ẋ(t) == [ x₂(t), x₁(t) + α*x₁(t)^2 + u(t) ]
    v^2 + ∫( 0.5u(t)^2 ) → min
end

Why?

Here is the error message:

Line 6: x(1) == [0, v]
UndefVarError: `v` not defined

Stacktrace:
 [1] macro expansion
   @ [~/.julia/packages/CTBase/rsUEs/src/onepass.jl:50](https://file+.vscode-resource.vscode-cdn.net/Users/ocots/Boulot/recherche/logiciels/dev/control-toolbox/OptimalControl/docs/src/~/.julia/packages/CTBase/rsUEs/src/onepass.jl:50) [inlined]
 [2] top-level scope
   @ [~/Boulot/recherche/logiciels/dev/control-toolbox/OptimalControl/docs/src/init.ipynb:8](https://file+.vscode-resource.vscode-cdn.net/Users/ocots/Boulot/recherche/logiciels/dev/control-toolbox/OptimalControl/docs/src/~/Boulot/recherche/logiciels/dev/control-toolbox/OptimalControl/docs/src/init.ipynb:8)

[jbcaillau]

et oui, hi hi 🫢

[jbcaillau]

@ocots Right-hand sides or, more generally, lower and upper values of box contraints, must be evaluable by Julia (must not contain variables, etc.) So this problem should be defined according to:

α = 5
@def ocp begin
    t ∈ [ 0, 1 ], time
    v ∈ R, variable
    x ∈ R², state
    u ∈ R, control
    x(0) == [ -1, 0 ]
    x(1) - [ 0, v ] == [ 0, 0 ]
    ẋ(t) == [ x₂(t), x₁(t) + α*x₁(t)^2 + u(t) ]
    v^2 + ∫( 0.5u(t)^2 ) → min
end

See also

This issue