added old MatrixGain definition for comparison

Author: Brad Carman

test/split_parameters.jl

@@ -137,6 +137,16 @@ x_costs = [
     model.inertia2.phi => 1.
 ]
 L = randn(1,4) # Post-multiply by `C` to get the correct input to the controller
+
+# This old definition of MatrixGain will work because the parameter space does not include K (an Array term)
+# @component function MatrixGainAlt(K::AbstractArray; name)
+#     nout, nin = size(K, 1), size(K, 2)
+#     @named input = RealInput(; nin = nin)
+#     @named output = RealOutput(; nout = nout)
+#     eqs = [output.u[i] ~ sum(K[i, j] * input.u[j] for j in 1:nin) for i in 1:nout]
+#     compose(ODESystem(eqs, t, [], []; name = name), [input, output])
+# end
+
 @named state_feedback = MatrixGain(K=-L) # Build negative feedback into the feedback matrix
 @named add = Add(;k1=1., k2=1.) # To add the control signal and the disturbance