From 207785ed1c4beaceb5f4cf99d878c03401af5aff Mon Sep 17 00:00:00 2001
From: Fredrik Bagge Carlson <cont-frb@ulund.org>
Date: Wed, 22 Dec 2021 08:08:13 +0100
Subject: [PATCH] scalar mul for tf

---
 src/types/TransferFunction.jl | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/types/TransferFunction.jl b/src/types/TransferFunction.jl
index d02acb591..7131537ab 100644
--- a/src/types/TransferFunction.jl
+++ b/src/types/TransferFunction.jl
@@ -133,10 +133,13 @@ end
 function *(G1::TransferFunction, G2::TransferFunction)
     # Note: G1*G2 = y <- G1 <- G2 <- u
     timeevol = common_timeevol(G1,G2)
-    if G1.nu != G2.ny
+    if G1.nu == G2.ny
+        matrix = G1.matrix * G2.matrix
+    elseif issiso(G1) || issiso(G2)
+        matrix = G1.matrix .* G2.matrix
+    else
         error("G1*G2: G1 must have same number of inputs as G2 has outputs")
     end
-    matrix = G1.matrix * G2.matrix
     return TransferFunction(matrix, timeevol)
 end