Reimplement automul

Project.toml

@@ -28,6 +28,7 @@ julia = "1.6"
 [extras]
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+Quantics = "87f76fb3-a40a-40c9-a63c-29fcfe7b7547"
 
 [targets]
-test = ["Test", "Random"]
+test = ["Test", "Random", "Quantics"]

src/ProjMPSs.jl

@@ -2,14 +2,14 @@ module ProjMPSs
 
 import OrderedCollections: OrderedSet, OrderedDict
 using EllipsisNotation
-import LinearAlgebra
+using LinearAlgebra: LinearAlgebra
 
-import ITensors: ITensors, Index, ITensor, dim, inds, qr, commoninds
-import ITensorMPS: ITensorMPS, AbstractMPS, MPS, MPO, siteinds
+import ITensors: ITensors, Index, ITensor, dim, inds, qr, commoninds, uniqueinds
+import ITensorMPS: ITensorMPS, AbstractMPS, MPS, MPO, siteinds, findsites
+import ITensors.TagSets: hastag, hastags
 
 import FastMPOContractions as FMPOC
 
-
 include("util.jl")
 include("projector.jl")
 include("projmps.jl")
@@ -18,4 +18,7 @@ include("patching.jl")
 include("contract.jl")
 include("adaptivemul.jl")
 
+# Only for backward compatibility
+include("automul.jl")
+
 end

src/automul.jl

@@ -0,0 +1,124 @@
+"""
+By default, elementwise multiplication will be performed.
+
+This function is kind of deprecated and will be removed in the future.
+"""
+function automul(
+    M1::BlockedMPS,
+    M2::BlockedMPS;
+    tag_row::String="",
+    tag_shared::String="",
+    tag_col::String="",
+    alg="naive",
+    maxdim=typemax(Int),
+    cutoff=1e-25,
+    kwargs...,
+)
+    all(length.(siteinds(M1)) .== 1) || error("M1 should have only 1 site index per site")
+    all(length.(siteinds(M2)) .== 1) || error("M2 should have only 1 site index per site")
+
+    sites_row = _findallsiteinds_by_tag(M1; tag=tag_row)
+    sites_shared = _findallsiteinds_by_tag(M1; tag=tag_shared)
+    sites_col = _findallsiteinds_by_tag(M2; tag=tag_col)
+    sites_matmul = Set(Iterators.flatten([sites_row, sites_shared, sites_col]))
+
+    sites1 = only.(siteinds(M1))
+    sites1_ewmul = setdiff(only.(siteinds(M1)), sites_matmul)
+    sites2_ewmul = setdiff(only.(siteinds(M2)), sites_matmul)
+    sites2_ewmul == sites1_ewmul || error("Invalid sites for elementwise multiplication")
+
+    M1 = _makesitediagonal(M1, sites1_ewmul; baseplev=1)
+    M2 = _makesitediagonal(M2, sites2_ewmul; baseplev=0)
+
+    sites_M1_diag = [collect(x) for x in siteinds(M1)]
+    sites_M2_diag = [collect(x) for x in siteinds(M2)]
+
+    M1 = rearrange_siteinds(M1, combinesites(sites_M1_diag, sites_row, sites_shared))
+
+    M2 = rearrange_siteinds(M2, combinesites(sites_M2_diag, sites_shared, sites_col))
+
+    M = contract(M1, M2; alg=alg, kwargs...)
+
+    M = extractdiagonal(M, sites1_ewmul)
+
+    ressites = Vector{eltype(siteinds(M1)[1])}[]
+    for s in siteinds(M)
+        s_ = unique(ITensors.noprime.(s))
+        if length(s_) == 1
+            push!(ressites, s_)
+        else
+            if s_[1] ∈ sites1
+                push!(ressites, [s_[1]])
+                push!(ressites, [s_[2]])
+            else
+                push!(ressites, [s_[2]])
+                push!(ressites, [s_[1]])
+            end
+        end
+    end
+    return truncate(rearrange_siteinds(M, ressites); cutoff=cutoff, maxdim=maxdim)
+end
+
+function combinesites(
+    sites::Vector{Vector{Index{IndsT}}},
+    site1::AbstractVector{Index{IndsT}},
+    site2::AbstractVector{Index{IndsT}},
+) where {IndsT}
+    length(site1) == length(site2) || error("Length mismatch")
+    for (s1, s2) in zip(site1, site2)
+        sites = combinesites(sites, s1, s2)
+    end
+    return sites
+end
+
+function combinesites(
+    sites::Vector{Vector{Index{IndsT}}}, site1::Index, site2::Index
+) where {IndsT}
+    sites = deepcopy(sites)
+    p1 = findfirst(x -> x[1] == site1, sites)
+    p2 = findfirst(x -> x[1] == site2, sites)
+    if p1 === nothing || p2 === nothing
+        error("Site not found")
+    end
+    if abs(p1 - p2) != 1
+        error("Sites are not adjacent")
+    end
+    deleteat!(sites, min(p1, p2))
+    deleteat!(sites, min(p1, p2))
+    insert!(sites, min(p1, p2), [site1, site2])
+    return sites
+end
+
+function _findallsiteinds_by_tag(M::BlockedMPS; tag=tag)
+    return findallsiteinds_by_tag(only.(siteinds(M)); tag=tag)
+end
+
+# The following code is copied from Quantics.jl
+
+function findallsiteinds_by_tag(
+    sites::AbstractVector{Index{T}}; tag::String="x", maxnsites::Int=1000
+) where {T}
+    _valid_tag(tag) || error("Invalid tag: $tag")
+    positions = findallsites_by_tag(sites; tag=tag, maxnsites=maxnsites)
+    return [sites[p] for p in positions]
+end
+
+function findallsites_by_tag(
+    sites::Vector{Index{T}}; tag::String="x", maxnsites::Int=1000
+)::Vector{Int} where {T}
+    _valid_tag(tag) || error("Invalid tag: $tag")
+    result = Int[]
+    for n in 1:maxnsites
+        tag_ = tag * "=$n"
+        idx = findall(hastags(tag_), sites)
+        if length(idx) == 0
+            break
+        elseif length(idx) > 1
+            error("Found more than one site indices with $(tag_)!")
+        end
+        push!(result, idx[1])
+    end
+    return result
+end
+
+_valid_tag(tag::String)::Bool = !occursin("=", tag)

src/blockedmps.jl

@@ -68,7 +68,6 @@ function Base.values(obj::BlockedMPS)
     return values(obj.data)
 end
 
-
 """
 Rearrange the site indices of the BlockedMPS according to the given order.
 If nessecary, tensors are fused or split to match the new order.
@@ -144,3 +143,26 @@ end
 function ITensorMPS.MPO(obj::BlockedMPS; cutoff=1e-25, maxdim=typemax(Int))::MPO
     return MPO(collect(MPS(obj; cutoff=cutoff, maxdim=maxdim, kwargs...)))
 end
+
+"""
+Make the BlockedMPS diagonal for a given site index `s` by introducing a dummy index `s'`.
+"""
+function makesitediagonal(obj::BlockedMPS, site)
+    return BlockedMPS([
+        _makesitediagonal(prjmps, site; baseplev=baseplev) for prjmps in values(obj)
+    ])
+end
+
+function _makesitediagonal(obj::BlockedMPS, site; baseplev=0)
+    return BlockedMPS([
+        _makesitediagonal(prjmps, site; baseplev=baseplev) for prjmps in values(obj)
+    ])
+end
+
+"""
+Extract diagonal of the BlockedMPS for `s`, `s'`, ... for a given site index `s`,
+where `s` must have a prime level of 0.
+"""
+function extractdiagonal(obj::BlockedMPS, site)
+    return BlockedMPS([extractdiagonal(prjmps, site) for prjmps in values(obj)])
+end

src/projmps.jl

@@ -189,3 +189,85 @@ end
 function LinearAlgebra.norm(M::ProjMPS)
     return _norm(MPS(M))
 end
+
+function _makesitediagonal(
+    projmps::ProjMPS, sites::AbstractVector{Index{IndsT}}; baseplev=0
+) where {IndsT}
+    M_ = deepcopy(MPO(collect(MPS(projmps))))
+    for site in sites
+        target_site::Int = only(findsites(M_, site))
+        M_[target_site] = _asdiagonal(M_[target_site], site; baseplev=baseplev)
+    end
+    return project(M_, projmps.projector)
+end
+
+function _makesitediagonal(projmps::ProjMPS, site::Index; baseplev=0)
+    return _makesitediagonal(projmps, [site]; baseplev=baseplev)
+end
+
+function makesitediagonal(projmps::ProjMPS, site::Index)
+    return _makesitediagonal(projmps, site; baseplev=0)
+end
+
+function makesitediagonal(projmps::ProjMPS, sites::AbstractVector{Index})
+    return _makesitediagonal(projmps, sites; baseplev=0)
+end
+
+function makesitediagonal(projmps::ProjMPS, tag::String)
+    mps_diagonal = makesitediagonal(MPS(projmps), tag)
+    projmps_diagonal = ProjMPS(mps_diagonal)
+
+    target_sites = findallsiteinds_by_tag(
+        unique(ITensors.noprime.(Iterators.flatten(siteinds(projmps)))); tag=tag
+    )
+
+    newproj = deepcopy(projmps.projector)
+    for s in target_sites
+        if isprojectedat(projmps.projector, s)
+            newproj[ITensors.prime(s)] = newproj[s]
+        end
+    end
+
+    return project(projmps_diagonal, newproj)
+end
+
+# FIXME: may be type unstable
+function _find_site_allplevs(tensor::ITensor, site::Index; maxplev=10)
+    ITensors.plev(site) == 0 || error("Site index must be unprimed.")
+    return [
+        ITensors.prime(site, plev) for
+        plev in 0:maxplev if ITensors.prime(site, plev) ∈ ITensors.inds(tensor)
+    ]
+end
+
+function extractdiagonal(
+    projmps::ProjMPS, sites::AbstractVector{Index{IndsT}}
+) where {IndsT}
+    tensors = collect(projmps.data)
+    for i in eachindex(tensors)
+        for site in intersect(sites, ITensors.inds(tensors[i]))
+            sitewithallplevs = _find_site_allplevs(tensors[i], site)
+            tensors[i] = if length(sitewithallplevs) > 1
+                tensors[i] = _extract_diagonal(tensors[i], sitewithallplevs...)
+            else
+                tensors[i]
+            end
+        end
+    end
+
+    projector = deepcopy(projmps.projector)
+    for site in sites
+        if site' in keys(projector.data)
+            delete!(projector.data, site')
+        end
+    end
+    return ProjMPS(MPS(tensors), projector)
+end
+
+
+function extractdiagonal(projmps::ProjMPS, tag::String)::ProjMPS
+    targetsites = findallsiteinds_by_tag(
+        unique(ITensors.noprime.(ProjMPSs._allsites(projmps))); tag=tag
+    )
+    return extractdiagonal(projmps, targetsites)
+end

src/util.jl

@@ -71,7 +71,6 @@ function _asdiagonal(t, site::Index{T}; baseplev=0)::ITensor where {T<:Number}
     )
 end
 
-
 function rearrange_siteinds(M::AbstractMPS, sites::Vector{Vector{Index{T}}})::MPS where {T}
     sitesold = siteinds(MPO(collect(M)))
 
@@ -104,5 +103,44 @@ function rearrange_siteinds(M::AbstractMPS, sites::Vector{Vector{Index{T}}})::MP
         tensors[i], t, _ = qr(t, linds)
     end
     tensors[end] *= t
-    MPS(tensors)
+    return MPS(tensors)
+end
+
+function _extract_diagonal(t, site::Index{T}, site2::Index{T}) where {T<:Number}
+    dim(site) == dim(site2) || error("Dimension mismatch")
+    restinds = uniqueinds(inds(t), site, site2)
+    newdata = zeros(eltype(t), dim.(restinds)..., dim(site))
+    olddata = Array(t, restinds..., site, site2)
+    for i in 1:dim(site)
+        newdata[.., i] = olddata[.., i, i]
+    end
+    return ITensor(newdata, restinds..., site)
+end
+
+
+"""
+Makes an MPS/MPO diagonal for a specified a site index `s`.
+On return, the data will be deep copied and the target core tensor will be diagonalized with an additional site index `s'`.
+"""
+function makesitediagonal(M::AbstractMPS, site::Index{T})::MPS where {T}
+    M_ = deepcopy(MPO(collect(M)))
+
+    target_site::Int = only(findsites(M_, site))
+    M_[target_site] = _asdiagonal(M_[target_site], site)
+
+    return MPS(collect(M_))
 end
+
+function makesitediagonal(M::AbstractMPS, tag::String)::MPS
+    M_ = deepcopy(MPO(collect(M)))
+    sites = siteinds(M_)
+
+    target_positions = findallsites_by_tag(siteinds(M_); tag=tag)
+
+    for t in eachindex(target_positions)
+        i, j = target_positions[t]
+        M_[i] = _asdiagonal(M_[i], sites[i][j])
+    end
+
+    return MPS(collect(M_))
+end