merge 10 naive algorithm in contractmpo

* <src/add>: added naive algorithm to contract_mpo_mpo

* <test/add>: naive test added

* Restrict test with JET to newer Julia versions

---------

Co-authored-by: Hiroshi Shinaoka <[email protected]>

Author: srohshap

src/contractMPO.jl

@@ -3,6 +3,8 @@ function contract_mpo_mpo(M1::MPO, M2::MPO; alg::String = "densitymatrix", kwarg
         return contract_densitymatrix(M1, M2; kwargs...)
     elseif alg == "fit"
         return contract_fit(M1, M2; kwargs...)
+    elseif alg == "naive"
+        return ITensors.contract(M1, M2; alg = "naive", kwargs...)
     else
         error("Unknown algorithm: $alg")
     end

src/fitalgorithm_sum.jl

@@ -198,14 +198,14 @@ function contract_operator_state_updater(
 end
 
 
-function contract_fit(input_state::MPS, init::MPS; coeff::Number=1, kwargs...)::MPS
+function contract_fit(input_state::MPS, init::MPS; coeff::Number = 1, kwargs...)::MPS
     links = ITensors.sim.(linkinds(init))
     init = replaceinds(linkinds, init, links)
     reduced_operator = ReducedFitProblem(input_state)
     return alternating_update(
         reduced_operator,
         init;
-        updater=contract_operator_state_updater,
+        updater = contract_operator_state_updater,
         kwargs...,
     )
 end
@@ -214,7 +214,7 @@ end
 function fit(
     input_states::AbstractVector{MPS},
     init::MPS;
-    coeffs::AbstractVector{<:Number}=ones(Int, length(input_states)),
+    coeffs::AbstractVector{<:Number} = ones(Int, length(input_states)),
     kwargs...,
 )::MPS
     links = ITensors.sim.(linkinds(init))
@@ -223,19 +223,19 @@ function fit(
     return alternating_update(
         reduced_operator,
         init;
-        updater=contract_operator_state_updater,
+        updater = contract_operator_state_updater,
         kwargs...,
     )
 end
 
 function fit(
     input_states::AbstractVector{MPO},
     init::MPO;
-    coeffs::AbstractVector{<:Number}=ones(Int, length(input_states)),
+    coeffs::AbstractVector{<:Number} = ones(Int, length(input_states)),
     kwargs...,
 )::MPO
     to_mps(Ψ::MPO) = MPS([x for x in Ψ])
 
-    res = fit(to_mps.(input_states), to_mps(init); coeffs=coeffs, kwargs...)
+    res = fit(to_mps.(input_states), to_mps(init); coeffs = coeffs, kwargs...)
     return MPO([x for x in res])
 end

test/naive.jl

@@ -0,0 +1,21 @@
+using Test
+
+import FastMPOContractions as FMPOC
+using ITensors
+
+
+
+@testset "naive (x-y-z)" begin
+    R = 3
+    sitesx = [Index(2, "Qubit,x=$n") for n = 1:R]
+    sitesy = [Index(2, "Qubit,y=$n") for n = 1:R]
+    sitesz = [Index(2, "Qubit,z=$n") for n = 1:R]
+
+    sitesa = collect(collect.(zip(sitesx, sitesy)))
+    sitesb = collect(collect.(zip(sitesy, sitesz)))
+    a = _random_mpo(sitesa)
+    b = _random_mpo(sitesb)
+    ab_ref = contract(a, b; alg = "naive")
+    ab = FMPOC.contract_mpo_mpo(a, b; alg = "naive")
+    @test ab_ref ≈ ab
+end

test/runtests.jl

@@ -10,3 +10,4 @@ include("densitymatrix.jl")
 include("fitalgorithm.jl")
 include("util.jl")
 include("fitalgorithm_sum.jl")
+include("naive.jl")

test/test_with_jet.jl

@@ -2,7 +2,7 @@ using JET
 import FastMPOContractions
 
 @testset "JET" begin
-    if VERSION ≥ v"1.9"
+    if VERSION ≥ v"1.10"
         JET.test_package(FastMPOContractions; target_defined_modules = true)
     end
 end