diff --git a/mathobjects.py b/mathobjects.py
index c708a3d..ff02823 100755
--- a/mathobjects.py
+++ b/mathobjects.py
@@ -79,6 +79,7 @@ class Func:
     return Add(self, other)
   def __truediv__(self, other):  # self / other
     return Div(self, other)
+  #TODO: change round to floor
   def __floordiv__(self, other): # self // other
     return Round(Div(self, other))
   def __pow__(self, other):      # self ** other
@@ -125,7 +126,7 @@ class Const(Func):
   def copy(self):
     return Const
   
-  def simplify(self):
+  def simplify(self): #TODO: return copy of itself
     return self
   
   def __str__(self):
@@ -145,7 +146,7 @@ class Var(Func):
   def copy(self):
     return Var
   
-  def simplify(self):
+  def simplify(self): #TODO: return copy of itself
     return self
   
   def __str__(self):
@@ -202,7 +203,7 @@ class Round(Func):
   def simplify(self):
     f = self.function.simplify()
     if isinstance(f, Const):
-      return Const(self.solve({}))
+      return Const(self.solve({})) #TODO: make use of the solved version
     else:
       return Round(f)
 
@@ -261,7 +262,7 @@ class Neg(Func):
       self.function = Const(function)
     else:
       self.function = function
-  
+
   def solve(self, vars):
     return -self.function.solve(vars)
 
@@ -273,10 +274,10 @@ class Neg(Func):
     if isinstance(f, Const):
       return Const(self.solve({}))
     else:
-      return Round(f)
+      return Neg(f)
   
   def __str__(self):
-    return "-" + addBrackets(self.function, 3) + ")"
+    return "-" + addBrackets(self.function, 3)
 
 # =================================================================
 # == Sub ==========================================================
@@ -341,7 +342,7 @@ class Eql(Func):
     return Eql
 
   def simplify(self):
-    if (    (isinstance(self.left,self.right.copy())) # same opperation
+    if (    (isinstance(self.left, self.right.copy())) # same opperation
         and (not isinstance(self.left, (Const, Var, Round))) # not const, var or Round
         and (self.left.right is self.right.right)): # subthing is the same
       return self.copy()(self.left.left.simplify(), self.right.left.simplify())
@@ -599,22 +600,34 @@ class Vec:
     ...
   def polar(self, *args):
     if len(args) == 2:
-      #   xy angle         xz angle         yz angle
-      self.x = math.sin(args[0][0]) * math.sin(args[0][1])
-      self.y = math.cos(args[0][0])                        * math.sin(args[0][2])
+      if not isinstance(args[0], (tuple, list)):
+        raise ValueError('Vec.polar(): first argument must be a tuple or list. ' + str(type(args[0])) + ' given')
+      if len(args[0]) < 3:
+        raise ValueError('Vec.polar(): first argument must be at least 3 items long')
+      if not isinstance(args[1], (int, float)):
+        raise ValueError('Vec.polar(): second argument must be a int or float. ' + str(type(args[1])) + ' given')
+      #        xy angle               xz angle               yz angle
+      self.x = math.sin(args[0][0]) #* math.sin(args[0][1])
+      self.y = math.cos(args[0][0]) #                       * math.sin(args[0][2])
       self.z =                        math.cos(args[0][1]) * math.cos(args[0][2])
-      self = self * l
+      self.mul(self, args[1])
     elif len(args) == 0:
       return (
         (
-          math.tanh(self.y, self.x),
-          math.tanh(self.z, self.x),
+          math.atan2(self.y, self.x),
+          math.atan2(self.z, self.x),
           0.0
         ),
         self.length(),
       )
+    else:
+      raise ValueError("Vec.polar(): Wrong number of arguments given. 2 or 0 suported")
   
   def rotate(self, angle):
+    if not isinstance(angle, (tuple, list)):
+      raise ValueError('Vec.rotate(): first argument must be a tuple or list')
+    if len(angle) < 3:
+      raise ValueError('Vec.rotate(): first argument must be at least 3 items long')
     p = self.polar()
     a = [p[0][0] + angle[0], p[0][1] + angle[1], p[0][2] + angle[2]]
     self.polar(a, p[1])
@@ -689,7 +702,7 @@ class Vec:
       print('WARNING: tried to add Vec with ' + str(type(other)))
       return other
 
-  def setitem(self, index, value):
+  def __setitem__(self, index, value):
     if(index == 0):
       self.x = value 
     elif(index == 1):
@@ -698,7 +711,7 @@ class Vec:
       self.z = value
     else:
       print('ERROR: tried to set index ' + str(index) + ' of a Vec')
-  def getitem(self, index):
+  def __getitem__(self, index):
     if(index == 0):
       return self.x
     elif(index == 1):
@@ -706,8 +719,7 @@ class Vec:
     elif(index == 2):
       return self.z
     else:
-      print('ERROR: tried to get index ' + str(index) + ' of a Vec')
-      return None
+      raise IndexError('tried to get index ' + str(index) + ' of a Vec')
 
   def __str__(self):
     return "Vec" + str(self.cartesian())