From 8a0b34e3aba7f85fae849b9252f29122f9c54183 Mon Sep 17 00:00:00 2001
From: Joey <joeytindall94@googlemail.com>
Date: Sun, 20 Oct 2024 17:52:00 +0100
Subject: [PATCH] Reverse edges in the reverse sweep of TDVP

---
 src/solvers/alternating_update/region_update.jl |  1 +
 src/solvers/insert/insert.jl                    |  3 +--
 src/solvers/sweep_plans/sweep_plans.jl          | 13 ++++++++-----
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/solvers/alternating_update/region_update.jl b/src/solvers/alternating_update/region_update.jl
index 6ad096b4..c741c82a 100644
--- a/src/solvers/alternating_update/region_update.jl
+++ b/src/solvers/alternating_update/region_update.jl
@@ -55,6 +55,7 @@ function region_update(
   #  drho = noise * noiseterm(PH, phi, ortho) # TODO: actually implement this for trees...
   # so noiseterm is a solver
   #end
+  #if isa(region, AbstractEdge) && 
   state, spec = inserter(state, phi, region; inserter_kwargs..., internal_kwargs)
   all_kwargs = (;
     which_region_update,
diff --git a/src/solvers/insert/insert.jl b/src/solvers/insert/insert.jl
index 42b32023..01fb35bd 100644
--- a/src/solvers/insert/insert.jl
+++ b/src/solvers/insert/insert.jl
@@ -33,8 +33,7 @@ end
 function default_inserter(
   state::AbstractTTN,
   phi::ITensor,
-  region::NamedEdge,
-  ortho;
+  region::NamedEdge;
   cutoff=nothing,
   maxdim=nothing,
   mindim=nothing,
diff --git a/src/solvers/sweep_plans/sweep_plans.jl b/src/solvers/sweep_plans/sweep_plans.jl
index 69221995..384cf8dc 100644
--- a/src/solvers/sweep_plans/sweep_plans.jl
+++ b/src/solvers/sweep_plans/sweep_plans.jl
@@ -13,10 +13,11 @@ end
 
 support(r) = r
 
-function reverse_region(edges, which_edge; nsites=1, region_kwargs=(;))
+function reverse_region(edges, which_edge; reverse_edge=false, nsites=1, region_kwargs=(;))
   current_edge = edges[which_edge]
   if nsites == 1
-    return [(current_edge, region_kwargs)]
+    !reverse_edge && return [(current_edge, region_kwargs)]
+    reverse_edge && return [(reverse(current_edge), region_kwargs)]
   elseif nsites == 2
     if last(edges) == current_edge
       return ()
@@ -62,6 +63,7 @@ function forward_sweep(
   dir::Base.ForwardOrdering,
   graph::AbstractGraph;
   root_vertex=GraphsExtensions.default_root_vertex(graph),
+  reverse_edges=false,
   region_kwargs,
   reverse_kwargs=region_kwargs,
   reverse_step=false,
@@ -71,12 +73,13 @@ function forward_sweep(
   regions = collect(
     flatten(map(i -> forward_region(edges, i; region_kwargs, kwargs...), eachindex(edges)))
   )
-
   if reverse_step
     reverse_regions = collect(
       flatten(
         map(
-          i -> reverse_region(edges, i; region_kwargs=reverse_kwargs, kwargs...),
+          i -> reverse_region(
+            edges, i; reverse_edge=reverse_edges, region_kwargs=reverse_kwargs, kwargs...
+          ),
           eachindex(edges),
         ),
       ),
@@ -90,7 +93,7 @@ end
 
 #ToDo: is there a better name for this? unidirectional_sweep? traversal?
 function forward_sweep(dir::Base.ReverseOrdering, args...; kwargs...)
-  return reverse(forward_sweep(Base.Forward, args...; kwargs...))
+  return reverse(forward_sweep(Base.Forward, args...; reverse_edges=true, kwargs...))
 end
 
 function default_sweep_plans(