Remove prime-level logic from apply, and use contract when primelevel…

… is not increased by operator.

src/treetensornetworks/solvers/contract.jl

@@ -74,33 +74,16 @@ end
 Overload of `ITensors.apply`.
 """
 function apply(tn1::AbstractTTN, tn2::AbstractTTN; init, kwargs...)
-  #plin=plev(first(externalinds(init)))
-  #outputindsnet=
-  #plout=plev(outputindsnet[first(vertices(outputindsnet))])
-  plev_inc = plev_diff(flatten_external_indsnetwork(tn1, tn2), external_indsnetwork(init))
-  init = prime(init, plev_inc)
+  init = init'
   tn12 = contract(tn1, tn2; init, kwargs...)
   return replaceprime(tn12, 1 => 0)
 end
 
 function sum_apply(
   tns::Vector{<:Tuple{<:AbstractTTN,<:AbstractTTN}}; alg="fit", init, kwargs...
 )
-  #plin=plev(first(externalinds(init)))
-  #outputindsnet = flatten_external_indsnetwork(first(tns), first(tn2s))
-  #plout=plev(outputindsnet[first(vertices(outputindsnet))])
-  plev_inc = plev_diff(
-    flatten_external_indsnetwork(first(first(tns)), last(first(tns))),
-    external_indsnetwork(init),
-  )
-  init = prime(init, plev_inc)
+  init = init'
   alg != "fit" && error("sum_apply not implemented for other algorithms than fit.")
   tn12 = contract(Algorithm(alg), tns; init, kwargs...)
   return replaceprime(tn12, 1 => 0)
 end
-
-function plev_diff(a::IndsNetwork, b::IndsNetwork)
-  pla = plev(only(a[first(vertices(a))]))
-  plb = plev(only(b[first(vertices(b))]))
-  return pla - plb
-end

test/test_treetensornetworks/test_solvers/test_contract.jl

@@ -46,16 +46,16 @@ using Test
     psit[j] *= delta(s[j], t[j])
   end
   # Test with nsweeps=3
-  Hpsi = apply(H, psi; alg="fit", init=psit, nsweeps=3)
+  Hpsi = contract(H, psi; alg="fit", init=psit, nsweeps=3)
   @test inner(psit, Hpsi) ≈ inner(psit, H, psi) atol = 1E-5
   # Test with less good initial guess MPS not equal to psi
   psi_guess = truncate(psit; maxdim=2)
-  Hpsi = apply(H, psi; alg="fit", nsweeps=4, init=psi_guess)
+  Hpsi = contract(H, psi; alg="fit", nsweeps=4, init=psi_guess)
   @test inner(psit, Hpsi) ≈ inner(psit, H, psi) atol = 1E-5
 
   # Test with nsite=1
   Hpsi_guess = random_mps(t; internal_inds_space=32)
-  Hpsi = apply(H, psi; alg="fit", init=Hpsi_guess, nsites=1, nsweeps=4)
+  Hpsi = contract(H, psi; alg="fit", init=Hpsi_guess, nsites=1, nsweeps=4)
   @test inner(psit, Hpsi) ≈ inner(psit, H, psi) atol = 1E-4
 end
 
@@ -93,17 +93,17 @@ end
   H = replaceinds(H, prime(s; links=[]) => t)
 
   # Test with nsweeps=2
-  Hpsi = apply(H, psi; alg="fit", init=psit, nsweeps=2)
+  Hpsi = contract(H, psi; alg="fit", init=psit, nsweeps=2)
   @test inner(psit, Hpsi) ≈ inner(psit, H, psi) atol = 1E-5
 
   # Test with less good initial guess MPS not equal to psi
   Hpsi_guess = truncate(psit; maxdim=2)
-  Hpsi = apply(H, psi; alg="fit", nsweeps=4, init=Hpsi_guess)
+  Hpsi = contract(H, psi; alg="fit", nsweeps=4, init=Hpsi_guess)
   @test inner(psit, Hpsi) ≈ inner(psit, H, psi) atol = 1E-5
 
   # Test with nsite=1
   Hpsi_guess = random_ttn(t; link_space=4)
-  Hpsi = apply(H, psi; alg="fit", nsites=1, nsweeps=4, init=Hpsi_guess)
+  Hpsi = contract(H, psi; alg="fit", nsites=1, nsweeps=4, init=Hpsi_guess)
   @test inner(psit, Hpsi) ≈ inner(psit, H, psi) atol = 1E-4
 end