docs: fix generate_control_function docs

Author: AayushSabharwal

docs/src/basics/InputOutput.md

@@ -70,7 +70,7 @@ Now we can test the generated function `f` with random input and state values
 p = [1]
 x = [rand()]
 u = [rand()]
-@test f[1](x, u, p, 1) ≈ -p[] * (x + u) # Test that the function computes what we expect D(x) = -k*(x + u)
+@test f(x, u, p, 1) ≈ -p[] * (x + u) # Test that the function computes what we expect D(x) = -k*(x + u)
 ```
 
 ## Generating an output function, ``g``

docs/src/tutorials/disturbance_modeling.md

@@ -184,7 +184,7 @@ disturbance_inputs = [ssys.d1, ssys.d2]
 P = ssys.system_model
 outputs = [P.inertia1.phi, P.inertia2.phi, P.inertia1.w, P.inertia2.w]
 
-(f_oop, f_ip), x_sym, p_sym, io_sys = ModelingToolkit.generate_control_function(
+f, x_sym, p_sym, io_sys = ModelingToolkit.generate_control_function(
     model_with_disturbance, inputs, disturbance_inputs; disturbance_argument = true)
 
 g = ModelingToolkit.build_explicit_observed_function(
@@ -195,12 +195,12 @@ x0, _ = ModelingToolkit.get_u0_p(io_sys, op, op)
 p = MTKParameters(io_sys, op)
 u = zeros(1) # Control input
 w = zeros(length(disturbance_inputs)) # Disturbance input
-@test f_oop(x0, u, p, t, w) == zeros(5)
+@test f(x0, u, p, t, w) == zeros(5)
 @test g(x0, u, p, 0.0) == [0, 0, 0, 0]
 
 # Non-zero disturbance inputs should result in non-zero state derivatives. We call `sort` since we do not generally know the order of the state variables
 w = [1.0, 2.0]
-@test sort(f_oop(x0, u, p, t, w)) == [0, 0, 0, 1, 2]
+@test sort(f(x0, u, p, t, w)) == [0, 0, 0, 1, 2]
 ```
 
 ## Input signal library

src/inputoutput.jl

@@ -160,16 +160,17 @@ has_var(ex, x) = x ∈ Set(get_variables(ex))
 # Build control function
 
 """
-    (f_oop, f_ip), x_sym, p_sym, io_sys = generate_control_function(
+    f, x_sym, p_sym, io_sys = generate_control_function(
             sys::AbstractODESystem,
             inputs             = unbound_inputs(sys),
             disturbance_inputs = nothing;
             implicit_dae       = false,
             simplify           = false,
         )
 
-For a system `sys` with inputs (as determined by [`unbound_inputs`](@ref) or user specified), generate a function with additional input argument `in`
+For a system `sys` with inputs (as determined by [`unbound_inputs`](@ref) or user specified), generate a function with additional input argument `u`
 
+The returned function `f` can be called in the out-of-place or in-place form:
 ```
 f_oop : (x,u,p,t)      -> rhs
 f_ip  : (xout,x,u,p,t) -> nothing
@@ -190,7 +191,7 @@ f, x_sym, ps = generate_control_function(sys, expression=Val{false}, simplify=fa
 p = varmap_to_vars(defaults(sys), ps)
 x = varmap_to_vars(defaults(sys), x_sym)
 t = 0
-f[1](x, inputs, p, t)
+f(x, inputs, p, t)
 ```
 """
 function generate_control_function(sys::AbstractODESystem, inputs = unbound_inputs(sys),

src/systems/optimal_control_interface.jl

@@ -50,7 +50,7 @@ function SciMLBase.ODEInputFunction{iip, specialize}(sys::ODESystem,
         initialization_data = nothing,
         cse = true,
         kwargs...) where {iip, specialize}
-    (f), _, _ = generate_control_function(
+    f, _, _ = generate_control_function(
         sys, inputs, disturbance_inputs; eval_module, cse, kwargs...)
 
     if tgrad