diff --git a/common.py b/common.py
index 722f8bd..cd77460 100644
--- a/common.py
+++ b/common.py
@@ -47,6 +47,7 @@ def _str(self, node, depth=0) -> str:
     (r'rref',               'OPR'),
     (r'solve',              'OPR'),
     (r'eval',               'OPR'),
+    (r'ls',                 'OPR'),
     (r'[a-zA-Z_]+',         'IDT'),
     (r'=',                  'EQL'),
     (r'\+',                 'ADD'),
diff --git a/tests.py b/tests.py
index 4843270..4a4c882 100644
--- a/tests.py
+++ b/tests.py
@@ -116,7 +116,7 @@ def runTest(self):
 
             self.assertTrue(sympy.Matrix(evaluate('identity({})'.format(r_dim), False)).equals(sympy.Identity(r_dim)))
 
-            for _ in range(1):
+            for _ in range(5):
                 print(_)
 
                 mat = [[more_zeroes(random.randint(0, 100)) for _ in range(r_dim)] for _ in range(r_dim)]
diff --git a/vartypes.py b/vartypes.py
index 1ba2996..04831e8 100644
--- a/vartypes.py
+++ b/vartypes.py
@@ -52,6 +52,12 @@ def identity(self):
     def solve(self, other):
         raise EvaluationException('Operation not defined for ' + self.type)
 
+    def eval(self, other):
+        raise EvaluationException('Operation not defined for ' + self.type)
+
+    def ls(self, other):
+        raise EvaluationException('Operation not defined for ' + self.type)
+
 
 class VariableValue(Value):
     def __init__(self, data):
@@ -188,16 +194,13 @@ def trans(self):
         return MatrixValue(list(map(list, zip(*self.value))))
 
     def cof(self):
-        # TODO: self code is pretty ugly.
-
         cofactor_matrix = []
-        mat = self.value
 
-        for row in range(len(mat)):
+        for row in range(len(self.value)):
             cofactor_matrix.append([])
 
-            for col in range(len(mat[row])):
-                minor = copy.deepcopy(mat)
+            for col in range(len(self.value[row])):
+                minor = copy.deepcopy(self.value)
                 del minor[row]
 
                 for r in minor:
@@ -234,6 +237,9 @@ def trnsform(self):
     def solve(self, other):
         return DynamicVectorValue(MatrixTransformer(copy.deepcopy(self.value)).rref(other.value[0])[2])
 
+    def ls(self, other):
+        return (self.trans().mul(self)).inv().mul(self.trans()).mul(other)
+
 
 class MatrixRowValue(Value):
     def __init__(self, data):