Wired input and output of function "c.amplitude" about tensorcircuit HOT 3 OPEN

Thanks for your reply.

I agree. Nothing is really wrong.

But I believe it is worthy to add a length check, because the error message of a (<n) binary string is:

"list index out of range"

and of a (>n+1) binary string is:

"The final node after contraction has more than one remaining edge. In this case output_edge_order has to be provided."

Neither of them is clear for a beginner.

I will give a try.

from tensorcircuit.

BTW, why tc.about() gives me "module 'tensorcircuit' has no attribute 'about'"?

you can upgrade you tensorcircuit version: pip install -U tensorcircuit.

Thanks for report the n+1 qubit input case for c.amplitude, can be reproduced, will have a look

from tensorcircuit.

turns out it is a feature related to tensornetwork, when there is only one disentangling edge (one extra bit string), the contractor doesn't raise error since unspecified output edge is unique.

See code below:

for n in [2, 3, 4]:
    ns = []
    for _ in range(n):
        ns.append(tc.gates.Gate(np.array([1.0, 0.0])))
    
    ns[0][0]^ns[1][0]
    try:
        print(n, tc.contractor(ns).tensor)
    except ValueError:
        print(n, "ValueError")

The output will be:

2 1.0
3 [1. 0.]
4 ValueError

If you really want to fix it (nothing really wrong if the use specify the correct bitstring), adding a length check at the beginning of amplitude method is enough. Welcome to PR on this error check protection

from tensorcircuit.