From b86c970dca698116db65788d238bab2922092c8a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jofre=20Vall=C3=A8s=20Muns?=
 <61060572+jofrevalles@users.noreply.github.com>
Date: Thu, 20 Jun 2024 13:32:12 +0200
Subject: [PATCH] Fix `leftsite` and `rightsite` for `adjoint` `Chain`s  (#50)

* Fix rightsite and leftsite for adjoint Chains

* Add tests for adjoint in Chain
---
 src/Ansatz/Chain.jl       | 13 ++++++++-----
 test/Ansatz/Chain_test.jl | 13 +++++++++++++
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/src/Ansatz/Chain.jl b/src/Ansatz/Chain.jl
index abb88aa..bb0ff55 100644
--- a/src/Ansatz/Chain.jl
+++ b/src/Ansatz/Chain.jl
@@ -183,19 +183,22 @@ function Base.convert(::Type{Chain}, qtn::Product)
 end
 
 leftsite(tn::Chain, site::Site) = leftsite(boundary(tn), tn, site)
-leftsite(::Open, tn::Chain, site::Site) = id(site) ∈ range(2, nlanes(tn)) ? Site(id(site) - 1) : nothing
-leftsite(::Periodic, tn::Chain, site::Site) = Site(mod1(id(site) - 1, nlanes(tn)))
+leftsite(::Open, tn::Chain, site::Site) =
+    id(site) ∈ range(2, nlanes(tn)) ? Site(id(site) - 1; dual = isdual(site)) : nothing
+leftsite(::Periodic, tn::Chain, site::Site) = Site(mod1(id(site) - 1, nlanes(tn)); dual = isdual(site))
 
 rightsite(tn::Chain, site::Site) = rightsite(boundary(tn), tn, site)
-rightsite(::Open, tn::Chain, site::Site) = id(site) ∈ range(1, nlanes(tn) - 1) ? Site(id(site) + 1) : nothing
-rightsite(::Periodic, tn::Chain, site::Site) = Site(mod1(id(site) + 1, nlanes(tn)))
+rightsite(::Open, tn::Chain, site::Site) =
+    id(site) ∈ range(1, nlanes(tn) - 1) ? Site(id(site) + 1; dual = isdual(site)) : nothing
+rightsite(::Periodic, tn::Chain, site::Site) = Site(mod1(id(site) + 1, nlanes(tn)); dual = isdual(site))
 
 leftindex(tn::Chain, site::Site) = leftindex(boundary(tn), tn, site)
 leftindex(::Open, tn::Chain, site::Site) = site == site"1" ? nothing : leftindex(Periodic(), tn, site)
 leftindex(::Periodic, tn::Chain, site::Site) = inds(tn; bond = (site, leftsite(tn, site)))
 
 rightindex(tn::Chain, site::Site) = rightindex(boundary(tn), tn, site)
-rightindex(::Open, tn::Chain, site::Site) = site == Site(nlanes(tn)) ? nothing : rightindex(Periodic(), tn, site)
+rightindex(::Open, tn::Chain, site::Site) =
+    site == Site(nlanes(tn); dual = isdual(site)) ? nothing : rightindex(Periodic(), tn, site)
 rightindex(::Periodic, tn::Chain, site::Site) = inds(tn; bond = (site, rightsite(tn, site)))
 
 Base.adjoint(chain::Chain) = Chain(adjoint(Quantum(chain)), boundary(chain))
diff --git a/test/Ansatz/Chain_test.jl b/test/Ansatz/Chain_test.jl
index d332397..1b7ab95 100644
--- a/test/Ansatz/Chain_test.jl
+++ b/test/Ansatz/Chain_test.jl
@@ -380,5 +380,18 @@
         isapprox(norm(qtn), 1.0)
     end
 
+    @testset "adjoint" begin
+        qtn = rand(Chain, Open, State; n = 5, p = 2, χ = 10)
+        adjoint_qtn = adjoint(qtn)
+
+        for i in 1:nsites(qtn)
+            i < nsites(qtn) &&
+                @test rightindex(adjoint_qtn, Site(i; dual = true)) == Symbol(String(rightindex(qtn, Site(i))) * "'")
+            i > 1 && @test leftindex(adjoint_qtn, Site(i; dual = true)) == Symbol(String(leftindex(qtn, Site(i))) * "'")
+        end
+
+        @test isapprox(contract(TensorNetwork(qtn)), contract(TensorNetwork(adjoint_qtn)))
+    end
+
     # TODO test `evolve!` methods
 end