You might have copied `a**2 + b**2 + c**2` and called them `p`? You can
check by typing `type(p)`. If it is an Add then that is what happened
somehow. It's always best to show the actual self-verifying code snippet.
Here is what I used and everything work for me:
```
>>> from sympy.vector
p.dot(p)
a**2 + b**2 + c**2
dot(p,p)
Traceback (most recent call last):
File "", line 1, in
File "C:\Users\Andreas
Schuldei\PycharmProjects\lissajous-achse\venv\lib\site-packages\sympy\physics\vector\functions.py",
line 31, in dot
raise TypeError('Dot product is between two vectors')
I don't see the exception that you showed:
In [9]: O = CoordSys3D('O')
...: r = O.x*O.i + O.y*O.j + O.z*O.k
...: dot(r,r) # this works
...: O.x**2 + O.y**2 + O.z**2
...: from sympy import symbols
...: a, b, c = symbols("a, b, c")
...: p = a*O.i +b*O.j + c*O.k
...: p
...:
