diff --git a/ME_2046/HW4/Figure_1.png b/ME_2046/HW4/Figure_1.png
new file mode 100644
index 0000000..9a05c53
Binary files /dev/null and b/ME_2046/HW4/Figure_1.png differ
diff --git a/ME_2046/HW4/hw4.py b/ME_2046/HW4/hw4.py
index ff97b00..0707180 100644
--- a/ME_2046/HW4/hw4.py
+++ b/ME_2046/HW4/hw4.py
@@ -54,6 +54,8 @@ sm.pprint(F)
 sm.pprint(G)
 sm.pprint(A)
 sm.pprint(B)
+print(sm.latex(A))
+print(sm.latex(B))
 
 ########################################################a
 print("PROBLEM 4:")
@@ -61,7 +63,7 @@ print("bilinear transform")
 T = 0.2  # s
 
 G_s = 10 / (s + 10)
-G_z = G_s.subs(s, 2 * (z - 1) / T * (z + 1))
+G_z = G_s.subs(s, 2 * (z - 1) / T / (z + 1))
 sm.pprint(G_z)
 sm.pprint(G_z.simplify())