"""This module defines discrete-time symbols.

Copyright 2020 Michael Hayes, UCECE

"""

from .sym import symsymbol

nsym = symsymbol('n', real=True)
ksym = symsymbol('k', real=True)
zsym = symsymbol('z', real=False)

dt = symsymbol('Delta_t', real=True)
df = symsymbol('Delta_f', real=True)

@@ -54,16 +54,23 @@
 ght 2020
+---2021
  Michael
@@ -139,20 +139,23 @@
 ol('n', 
-real
+integer
 =True)%0Ak
@@ -175,20 +175,23 @@
 ol('k', 
-real
+integer
 =True)%0Az

Ensure that n and k are integer