compress printing for very large statespace models

lib/ControlSystemsBase/src/types/StateSpace.jl

@@ -564,18 +564,18 @@ end
 Base.print(io::IO, sys::AbstractStateSpace) = show(io, sys)
 
 function Base.show(io::IO, sys::AbstractStateSpace)
-    # Compose the name vectors
-    #inputs = format_names(s.inputnames, "u", "?")
-    #outputs = format_names(s.outputnames, "y", "?")
-    #println(io, "StateSpace:")
     println(io, typeof(sys))
+    A, B, C, D = ssdata(sys)
     if nstates(sys) > 0
-        #states = format_names(s.statenames, "x", "?")
-        println(io, "A = \n", _string_mat_with_headers(sys.A))
-        println(io, "B = \n", _string_mat_with_headers(sys.B))
-        println(io, "C = \n", _string_mat_with_headers(sys.C))
+        length(A) < 200 ? println(io, "A = \n", _string_mat_with_headers(A)) :
+            println(io, "A = $(typeof(A))$(size(A))")
+        length(B) < 200 ? println(io, "B = \n", _string_mat_with_headers(B)) :
+            println(io, "B = $(typeof(B))$(size(B))")
+        length(C) < 200 ? println(io, "C = \n", _string_mat_with_headers(C)) :
+            println(io, "C = $(typeof(C))$(size(C))")
     end
-    println(io, "D = \n", _string_mat_with_headers(sys.D), "\n")
+    length(D) < 200 ? println(io, "D = \n", _string_mat_with_headers(D), "\n") :
+        println(io, "D = ", iszero(D) ? "  0" : "$(typeof(D))$(size(D))", "\n")
     # Print sample time
     if isdiscrete(sys)
         println(io, "Sample Time: ", sys.Ts, " (seconds)")

lib/ControlSystemsBase/test/test_statespace.jl

@@ -221,6 +221,20 @@
             @test sprint(show, C_022) == "StateSpace{Continuous, Float64}\nD = \n 4.0  0.0\n 0.0  4.0\n\nContinuous-time state-space model"
             @test sprint(show, D_022) == "StateSpace{Discrete{Float64}, Float64}\nD = \n 4.0  0.0\n 0.0  4.0\n\nSample Time: 0.005 (seconds)\nDiscrete-time state-space model"
             @test sprint(show, D_222) == "StateSpace{Discrete{Float64}, Float64}\nA = \n  0.2  -0.8\n -0.8   0.07\nB = \n 1.0  0.0\n 0.0  2.0\nC = \n 1.0  0.0\n 0.0  1.0\nD = \n 0.0  0.0\n 0.0  0.0\n\nSample Time: 0.005 (seconds)\nDiscrete-time state-space model"
+
+            # Large systems use a compressed format
+            G_large_zeroD = ss(zeros(15,15), zeros(15,15), zeros(15,15), zeros(15,15))
+            @test sprint(show, G_large_zeroD) == "StateSpace{Continuous, Float64}\nA = Matrix{Float64}(15, 15)\nB = Matrix{Float64}(15, 15)\nC = Matrix{Float64}(15, 15)\nD =   0\n\nContinuous-time state-space model"
+
+            G_large_nonzeroD = ss(zeros(15,15), zeros(15,15), zeros(15,15), ones(15,15))
+            @test sprint(show, G_large_nonzeroD) == "StateSpace{Continuous, Float64}\nA = Matrix{Float64}(15, 15)\nB = Matrix{Float64}(15, 15)\nC = Matrix{Float64}(15, 15)\nD = Matrix{Float64}(15, 15)\n\nContinuous-time state-space model"
+
+            G_large_A = ss(zeros(15,15), zeros(15,1), zeros(1,15), 0)
+            out_large_A = sprint(show, G_large_A)
+            @test occursin("A = Matrix{Float64}(15, 15)", out_large_A)
+            @test occursin("B = \n", out_large_A)
+            @test occursin("C = \n", out_large_A)
+            @test occursin("D = \n", out_large_A)
         end
 
         G = ssrand(1,2,3)