diff --git a/linalg-practice.py b/linalg-practice.py
index 2b2c8f3..9f7c032 100644
--- a/linalg-practice.py
+++ b/linalg-practice.py
@@ -54,6 +54,9 @@ def eigcheck(a, b, rowcol, intmax):
             return False
     return True
 
+def diagcheck(a, b, rowcol, intmax):
+    return (a.diagonalize()[1] == sp.Matrix(inmat(rowcol)))
+
 # practice function
 def practice(t) :
     count = 0
@@ -70,6 +73,8 @@ def practice(t) :
         f = invcheck
     elif t == "eig" :
         f = eigcheck
+    elif t == "diag" :
+        f = diagcheck
     else :
         exit()
 
@@ -83,6 +88,10 @@ def practice(t) :
 
         # infinite loop until user succeeds 
         while True :
+            # if diagcheck, make sure the matrix is diagonalizable
+            if t == "diag" :
+                while not a.is_diagonalizable :
+                    a = genmatrix(rowcol, intmax, dif)
             sp.pprint(a)
             # if return of function is True
             if f(a, b, rowcol, intmax) :
@@ -100,5 +109,5 @@ def practice(t) :
                 continue
 
 # take input from user on the type of practice they want to do
-t = input("What do you want to practice? (mult, det, inv, eig) ")
+t = input("What do you want to practice? (mult, det, inv, eig, diag) ")
 practice(t)