Can not define Kronecker delta using Jupyter notebook

Question

Hi

When I type

in: KroneckerDelta;

the delta symbols is printed, but when I type

in: \delta{#}::KroneckerDelta;

out: TokenError: ('EOF in multi-line statement', (2, 0))

At: /home/irvin/miniconda3/lib/python3.7/tokenize.py(579): _tokenize

When I run same line in cadabra interface have no problem. I do not have any other problem using cadabra on the notebook and don't have a clue on how to solve it.

Thanks

Answer 1

Are you sure you are using a Cadabra kernel, not a standard Python kernel? What does

print(__cdbkernel__.version)

show when you evaluate it in a cell?

Comments

Thanks. Yes I am using a Cadabra kernel

in: print(cdbkernel.version)

out: 2.3.0

I opened a new Cadabra Kernel and was able to define kronecker delta. In the previous notebook I was using also sympy and might have done something that prevented from defining the kronecker delta.

---

Indeed, if you do

from sympy import *

then

\delta{#}::KroneckerDelta;

fails. I haven't chased this down yet. In general, you are running all sorts of risks by doing a blanket import like that first line above (not just with sympy), as it can overwrite any symbols/functions that are already present. It's better to do

import sympy as sp

or something like that (and in fact Cadabra already does import sympy for you).

---

Makes sense. Many thanks