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Fix full_update for tensors with dangling indices #4

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Merged
mtfishman merged 1 commit into from
Jul 10, 2026
Merged

Fix full_update for tensors with dangling indices #4

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2 changes: 1 addition & 1 deletion Project.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@ TypeParameterAccessors = "7e5a90cf-f82e-492e-a09b-e3e26432c138"
Adapt = "4.3.0"
Dictionaries = "0.4"
Graphs = "1.8.0"
ITensorBase = "0.11.2"
ITensorBase = "0.11.3"
KrylovKit = "0.10.2"
LinearAlgebra = "1.11.0"
MatrixAlgebraKit = "0.6.8"
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14 changes: 10 additions & 4 deletions src/Apply/full_update.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -125,8 +125,14 @@ function optimise_p_q(
qs_ind = setdiff(inds(q_cur), collect(Iterators.flatten(inds.(vcat(envs, p_cur)))))
ps_ind = setdiff(inds(p_cur), collect(Iterators.flatten(inds.(vcat(envs, q_cur)))))

function b(p::ITensor, q::ITensor, o::ITensor, envs::Vector{ITensor}, r::ITensor)
ts = vcat(ITensor[p, q, o, conj(prime(r))], envs)
function b(p::ITensor, q::ITensor, o::ITensor, envs::Vector{ITensor}, r::ITensor, s_ind)
# `r`'s solve indices that the gate `o` does not act on are dangling spectator legs
# (e.g. the length-1 auxiliary index that makes a definite-charge site tensor
# symmetry-invariant). Un-prime them on the bra so they trace against the ket instead
# of surviving as duplicate names under `noprime`.
spectator = setdiff(s_ind, inds(o))
r_bra = replaceinds(conj(prime(r)), (prime.(spectator) .=> spectator)...)
ts = vcat(ITensor[p, q, o, r_bra], envs)
sequence = contraction_sequence(ts; alg = "optimal")
return noprime(contract_network(ts; sequence))
end
Expand All @@ -142,14 +148,14 @@ function optimise_p_q(
return noprime(contract_network(ts; sequence))
end
for i in 1:nfullupdatesweeps
b_vec = b(p, q, o, envs, q_cur)
b_vec = b(p, q, o, envs, q_cur, qs_ind)
M_p_partial = partial(M_p, envs, q_cur, qs_ind)

p_cur, info = linsolve(
M_p_partial, b_vec, p_cur; isposdef = envisposdef, ishermitian = false
)

b_tilde_vec = b(p, q, o, envs, p_cur)
b_tilde_vec = b(p, q, o, envs, p_cur, ps_ind)
M_p_tilde_partial = partial(M_p, envs, p_cur, ps_ind)

q_cur, info = linsolve(
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