Use @preserve_graph ingauge_edge(Algorithm::"orthogonalize", tn::AbstractITensorNetwork, edge, ...) and truncate(tn::AbstractITensorNetwork, edge, ...) (ITensor#237)

Author: JoeyT1994

Project.toml

@@ -1,7 +1,7 @@
 name = "ITensorNetworks"
 uuid = "2919e153-833c-4bdc-8836-1ea460a35fc7"
 authors = ["Matthew Fishman <mfishman@flatironinstitute.org>, Joseph Tindall <jtindall@flatironinstitute.org> and contributors"]
-version = "0.13.8"
+version = "0.13.9"
 
 [deps]
 AbstractTrees = "1520ce14-60c1-5f80-bbc7-55ef81b5835c"

src/abstractitensornetwork.jl

@@ -603,12 +603,13 @@ function gauge_edge(
   # # TODO: Implement as `only(common_neighbors(tn, src(edge), dst(edge)))`
   # new_vertex = only(neighbors(tn, src(edge)) ∩ neighbors(tn, dst(edge)))
   # return contract(tn, new_vertex => dst(edge))
+  !has_edge(tn, edge) && throw(ArgumentError("Edge not in graph."))
   tn = copy(tn)
   left_inds = uniqueinds(tn, edge)
   ltags = tags(tn, edge)
   X, Y = factorize(tn[src(edge)], left_inds; tags=ltags, ortho="left", kwargs...)
-  tn[src(edge)] = X
-  tn[dst(edge)] *= Y
+  @preserve_graph tn[src(edge)] = X
+  @preserve_graph tn[dst(edge)] = tn[dst(edge)]*Y
   return tn
 end
 
@@ -677,12 +678,13 @@ end
 
 # TODO: decide whether to use graph mutating methods when resulting graph is unchanged?
 function _truncate_edge(tn::AbstractITensorNetwork, edge::AbstractEdge; kwargs...)
+  !has_edge(tn, edge) && throw(ArgumentError("Edge not in graph."))
   tn = copy(tn)
   left_inds = uniqueinds(tn, edge)
   ltags = tags(tn, edge)
   U, S, V = svd(tn[src(edge)], left_inds; lefttags=ltags, kwargs...)
-  tn[src(edge)] = U
-  tn[dst(edge)] *= (S * V)
+  @preserve_graph tn[src(edge)] = U
+  @preserve_graph tn[dst(edge)] = tn[dst(edge)] * (S*V)
   return tn
 end