algebraic operations for BaseNode

[mganahl]

It would be convenient to have addition, subtraction, multiplication by scalar and division by scalar for BaseNodes:

a, b =tn.Node(np.random.rand(3,3)), tn.Node(np.random.rand(3,3))
c=a + b
d = a*10
e = a/5

[miriyalavignesh]

Hey I want to work on this issue, I am guessing this should be little bit straight forward. Since this is mostly implementing operator overloading for TensorNetwork, please let me know if there are more caveats which are not obvious.

[chaserileyroberts]

Great! Go for it.

Yes you'll need to overload the Node classes __add__, __mul__ etc methods and then modifying the underlying tensors based on their backends. I would recommend adding them to the BaseNode class and throwing NotImplemented errors for node types that don't support these types of ops. (For example, CopyNode shouldn't support these operations.)

You'll then need to add the add, multiply, etc operations to BaseBackend and then add them to the concrete backend classes.

[IllgamhoDuck]

@Thenerdstation How is this issue going on? I checked the PR of this issue but seems not merged yet. Seems add, sub is made and mul, div yet can I work on this issue?