Ryan Levy

Here's a bug I've run into: ```C++ int N=6; auto sites=SpinHalf(N); auto state = InitState(sites); for (auto j: range1(N)) (j%2==0) ? state.set(j,"Up") : state.set(j,"Dn"); auto psi = MPS(state); auto ampo...

Add AutoMPO concat function for local operators

1

Addressing #219 and [this forum post](http://itensor.org/support/1212/autompo-syntax-concatenate-local-terms?show=1212), this provides a concatenation function for local operators and `AutoMPO` Usage: ```c++ auto ampo = AutoMPO(sites); //loop in a function for(auto n: range1(N)) ampo.concat("Sz",n);...

Infinite loop within tensor cross

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#### Describe the bug For certain rank inputs to `tensor_train_cross` the algorithm gets stuck in a [while loop](https://github.com/tensorly/tensorly/blob/main/tensorly/contrib/decomposition/_tt_cross.py#L127). #### Steps or Code to Reproduce ```python import numpy as np import...

[From the [forum here](https://itensor.discourse.group/t/vumps-mpo-error/1660/) ] The following OpSum appears to break the code due to a single Op not being wrapped into a `sum` ```julia function ITensorInfiniteMPS.unit_cell_terms(::Model"bad") opsum = OpSum()...