expand docs for named ss

Author: baggepinnen

docs/src/index.md

@@ -54,21 +54,23 @@ pkg> add RobustAndOptimalControl
 ```
 
 ## Named systems
-See [complicated-feedback example](https://github.com/JuliaControl/RobustAndOptimalControl.jl/blob/master/examples/complicated_feedback.jl)
-- [`named_ss`](@ref)
 
-Named systems can be indexed with their names, e.g.,
-```julia
-G[:y2, :u4]
+Named systems can be created with [`named_ss`](@ref) and indexed with their names, e.g.,
+```@repl
+G = ssrand(2,2,2);
+s1 = named_ss(G, x = :x, u = [:u_temp, :u_current]) # Create a named system
+s1[:y1, :u_temp] # Access inputs and outputs using their names
 ```
 but also using incomplete names, e.g., if `G` contains outputs `:y1, :y2, :y3, :z1, :z2`, the following retrieves the three outputs that has the prefix `:y`
-```julia
-G[:y, :] # Prefix matching is used if no exact match is found.
+```@repl
+s1[:y, :] # Prefix matching is used if no exact match is found.
 ```
 
+See [complicated-feedback example](https://github.com/JuliaControl/RobustAndOptimalControl.jl/blob/master/examples/complicated_feedback.jl) as well as the example under [Connecting systems together](@ref) below for additional examples.
+
 ## Connecting systems together
-See [complicated-feedback example](https://github.com/JuliaControl/RobustAndOptimalControl.jl/blob/master/examples/complicated_feedback.jl)
-- [`connect`](@ref)
+Advanced interconnected systems can be created using the function [`connect`](@ref). 
+See [complicated-feedback example](https://github.com/JuliaControl/RobustAndOptimalControl.jl/blob/master/examples/complicated_feedback.jl) as well as the following example:
 
 ### Example
 The following complicated feedback interconnection

src/named_systems2.jl

@@ -116,15 +116,16 @@ Base.:^(s::Symbol, n::Int) = expand_symbol(s, n)
 """
     named_ss(sys::AbstractStateSpace{T}; x, u, y)
 
-Create a `NamedStateSpace` system. This kind of system uses names rather than integer indices to refer to states, inputs and outputs
+Create a `NamedStateSpace` system. This kind of system uses names rather than integer indices to refer to states, inputs and outputs.
+- If a single name is provided but a vector of names is expected, this name will be used as prefix followed by a numerical index.
+- If no name is provided, default names (`x,y,u`) will be used.
 
 # Arguments:
 - `sys`: A system to add names to.
 - `x`: A list of symbols with names of the states.
 - `u`: A list of symbols with names of the inputs.
 - `y`: A list of symbols with names of the outputs.
 
-Default names of signals if none are provided are `x,u,y`.
 
 # Example
 ```julia
@@ -133,7 +134,7 @@ G2 = ss(1,1,1,0)
 s1 = named_ss(G1, x = :x, u = :u1, y=:y1)
 s2 = named_ss(G2, x = :z, u = :u2, y=:y2)
 
-s1[:y1, :u1] # Index using symbols
+s1[:y1, :u1] # Index using symbols. Uses prefix matching if no exact match is found.
 
 fb = feedback(s1, s2, r = :r) # 
 ```
@@ -163,7 +164,7 @@ end
 """
     named_ss(sys::AbstractStateSpace, name; x, y, u)
 
-If a single name is provided, the outputs, inputs and states will be automatically named
+If a single name of the system is provided, the outputs, inputs and states will be automatically named
 `y,u,x` with `name` as prefix.
 """
 function named_ss(sys::AbstractStateSpace, name;