Bug fix in current ortho. Change test

src/solvers/alternating_update/region_update.jl

@@ -7,36 +7,27 @@ function current_ortho(sweep_plan, which_region_update)
   if !isa(region, AbstractEdge) && length(region) == 1
     return only(current_verts)
   end
-  if which_region_update == length(regions)
-    # look back by one should be sufficient, but may be brittle?
-    overlapping_vertex = only(
-      intersect(current_verts, support(regions[which_region_update - 1]))
-    )
-    return overlapping_vertex
-  else
-    # look forward
-    other_regions = filter(
-      x -> !(issetequal(x, current_verts)), support.(regions[(which_region_update + 1):end])
+  # look forward
+  other_regions = filter(
+    x -> !(issetequal(x, current_verts)), support.(regions[(which_region_update + 1):end])
+  )
+  # find the first region that has overlapping support with current region 
+  ind = findfirst(x -> !isempty(intersect(support(x), support(region))), other_regions)
+  if isnothing(ind)
+    # look backward
+    other_regions = reverse(
+      filter(
+        x -> !(issetequal(x, current_verts)), support.(regions[1:(which_region_update - 1)])
+      ),
     )
-    # find the first region that has overlapping support with current region 
     ind = findfirst(x -> !isempty(intersect(support(x), support(region))), other_regions)
-    if isnothing(ind)
-      # look backward
-      other_regions = reverse(
-        filter(
-          x -> !(issetequal(x, current_verts)),
-          support.(regions[1:(which_region_update - 1)]),
-        ),
-      )
-      ind = findfirst(x -> !isempty(intersect(support(x), support(region))), other_regions)
-    end
-    @assert !isnothing(ind)
-    future_verts = union(support(other_regions[ind]))
-    # return ortho_ceter as the vertex in current region that does not overlap with following one
-    overlapping_vertex = intersect(current_verts, future_verts)
-    nonoverlapping_vertex = only(setdiff(current_verts, overlapping_vertex))
-    return nonoverlapping_vertex
   end
+  @assert !isnothing(ind)
+  future_verts = union(support(other_regions[ind]))
+  # return ortho_ceter as the vertex in current region that does not overlap with following one
+  overlapping_vertex = intersect(current_verts, future_verts)
+  nonoverlapping_vertex = only(setdiff(current_verts, overlapping_vertex))
+  return nonoverlapping_vertex
 end
 
 function region_update(

test/test_treetensornetworks/test_solvers/test_dmrg.jl

@@ -1,7 +1,7 @@
 @eval module $(gensym())
 using DataGraphs: edge_data, vertex_data
 using Dictionaries: Dictionary
-using Graphs: nv, vertices
+using Graphs: nv, vertices, uniform_tree
 using ITensorMPS: ITensorMPS
 using ITensorNetworks:
   ITensorNetworks,
@@ -19,6 +19,7 @@ using ITensorNetworks.ITensorsExtensions: replace_vertices
 using ITensorNetworks.ModelHamiltonians: ModelHamiltonians
 using ITensors: ITensors
 using KrylovKit: eigsolve
+using NamedGraphs: NamedGraph, rename_vertices
 using NamedGraphs.NamedGraphGenerators: named_comb_tree
 using Observers: observer
 using StableRNGs: StableRNG
@@ -313,11 +314,12 @@ end
   nsites = 2
   nsweeps = 10
 
-  c = named_comb_tree((3, 2))
-  s = siteinds("S=1/2", c)
-  os = ModelHamiltonians.heisenberg(c)
-  H = ttn(os, s)
   rng = StableRNG(1234)
+  g = NamedGraph(uniform_tree(10))
+  g = rename_vertices(v -> (v, 1), g)
+  s = siteinds("S=1/2", g)
+  os = ModelHamiltonians.heisenberg(g)
+  H = ttn(os, s)
   psi = random_ttn(rng, s; link_space=5)
   e, psi = dmrg(H, psi; nsweeps, maxdim, nsites)