Adds another state to this state as \( |\psi \rangle \to |\psi\rangle + |\textrm{other}\rangle\).
other | the added state |
MPS can be added using a tensor addition for each physical index, which is implemented below. The state can then usually be truncated very easily, but this is not done in the function itself.
References syten::expansion(), syten::genCombinator(), lIdx, lInt, maybeCache(), rIdx, rInt, size(), SYTEN_ASSERT, uInt, and syten::validateTensorEdge().