sympy.simplify(mv) blows up with Recursion

[eric-wieser]

>>> ga, e1, e2, e3, ep, en = galgebra.ga.Ga.build('e_1 e_2 e_3 e_{+} e_{-}',g=[1,1,1, 1, -1])
>>> sympy.simplify(e1)
RecursionError: maximum recursion depth exceeded while calling a Python object
>>> list(e1)
RecursionError: maximum recursion depth exceeded while calling a Python object

This is because:

• sympy.simplify and list calls iter(e1)
• Mv.__iter__ is not defined, so it defaults to:

  def __iter__(self):
      i = 0
      while True:
          try:
              yield self[i]
          except IndexError:
              break
          i += 1
  ```
  

• Mv.__getitem__ will return 0 forever, as it implies grade selection

Possible fixes:

• Have Mv.__iter__ raise TypeError
• Have Mv.__iter__ iterate only up to the highest grade present

[eric-wieser]

Using the TypeError approach doesn't improve things much:

>>> sympy.simplify(e1)*e1

[meuns]

sympy.simplify(e1.obj) should do the trick