refactor: add inputs to the interpolation components

Co-authored-by: Fredrik Bagge Carlson <[email protected]>

Author: SebastianM-C

src/Blocks/sources.jl

@@ -752,24 +752,25 @@ such as `LinearInterpolation`, `ConstantInterpolation` or `CubicSpline`.
 
 # Parameters:
   - `interpolator`: the symbolic
-  - `t`: the parameter used for interpolation
 
 # Connectors:
+  - `input`: a [`RealInput`](@ref) connector corresponding to the independent variable
   - `output`: a [`RealOutput`](@ref) connector corresponding to the interpolated value
 """
 function Interpolation(interp_type, u, x, args...; name)
     itp = interp_type(u, x, args...)
-    InterpolationBlock(itp; name, t)
+    Interpolation(itp; name)
 end
 
 function Interpolation(itp; name)
     @parameters (interpolator::typeof(itp))(..) = itp
-
+    @named input = RealInput()
     @named output = RealOutput()
 
-    eqs = [output.u ~ interpolator(t)]
+    eqs = [output.u ~ interpolator(input.u)]
 
-    ODESystem(eqs, ModelingToolkit.t_nounits, [], [interpolator, t]; name, systems = [output])
+    ODESystem(
+        eqs, t, [], [interpolator]; name, systems = [input, output])
 end
 
 struct CachedInterpolation{T,I,U,X,C}
@@ -840,36 +841,35 @@ such as `LinearInterpolation`, `ConstantInterpolation` or `CubicSpline`.
   - `args`: any other arguments beeded to build the interpolation
 # Keyword arguments:
   - `name`: the name of the component
-  - `t`: the interpolation parameter, this is the time (`ModelingToolkit.t_nounits`) by default
 
 # Parameters:
   - `data`: the symbolic representation of the data passed at construction time via `u`.
   - `ts`: the symbolic representation of times corresponding to the data passed at construction time via `x`.
-  - `t`: the parameter used for interpolation
 
 # Connectors:
+  - `input`: a [`RealInput`](@ref) connector corresponding to the independent variable
   - `output`: a [`RealOutput`](@ref) connector corresponding to the interpolated value
 """
 function ParametrizedInterpolation(
         interp_type::T, u::AbstractVector, x::AbstractVector, args...;
-        name, t = ModelingToolkit.t_nounits) where {T}
-
+        name) where {T}
     build_interpolation = CachedInterpolation(interp_type, u, x, args)
 
     @parameters data[1:length(x)] = u
     @parameters ts[1:length(x)] = x
     @parameters interpolation_type::T=interp_type [tunable = false]
     @parameters (interpolator::interp_type)(..)::eltype(u)
 
+    @named input = RealInput()
     @named output = RealOutput()
 
-    eqs = [output.u ~ interpolator(t)]
+    eqs = [output.u ~ interpolator(input.u)]
 
     ODESystem(eqs, ModelingToolkit.t_nounits, [],
-        [data, ts, interpolation_type, interpolator, t];
+        [data, ts, interpolation_type, interpolator];
         parameter_dependencies = [
             interpolator ~ build_interpolation(data, ts, args)
         ],
-        systems = [output],
+        systems = [input, output],
         name)
 end

test/Blocks/sources.jl

@@ -488,7 +488,7 @@ end
     x = 0:14.0
 
     @named i = Interpolation(LinearInterpolation, u, x)
-    eqs = [D(y) ~ i.output.u]
+    eqs = [i.input.u ~ t, D(y) ~ i.output.u]
 
     @named model = ODESystem(eqs, t, systems = [i])
     sys = structural_simplify(model)
@@ -506,7 +506,7 @@ end
 
     @testset "LinearInterpolation" begin
         @named i = ParametrizedInterpolation(LinearInterpolation, u, x)
-        eqs = [D(y) ~ i.output.u]
+        eqs = [i.input.u ~ t, D(y) ~ i.output.u]
 
         @named model = ODESystem(eqs, t, systems = [i])
         sys = structural_simplify(model)
@@ -556,7 +556,7 @@ end
     @testset "BSplineInterpolation" begin
         @named i = ParametrizedInterpolationBlock(
             BSplineInterpolation, u, x, 3, :Uniform, :Uniform)
-        eqs = [D(y) ~ i.output.u]
+        eqs = [i.input.u ~ t, D(y) ~ i.output.u]
 
         @named model = ODESystem(eqs, t, systems = [i])
         sys = structural_simplify(model)