Parallel TCI, Parallel zipup, Fit, Parallel fit and minor functions

.gitignore

@@ -3,3 +3,5 @@
 *.jl.mem
 /Manifest.toml
 /docs/build/
+LocalPreferences.toml
+.vscode/settings.json

Project.toml

@@ -7,6 +7,7 @@ version = "0.9.17"
 BitIntegers = "c3b6d118-76ef-56ca-8cc7-ebb389d030a1"
 EllipsisNotation = "da5c29d0-fa7d-589e-88eb-ea29b0a81949"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+MPI = "da04e1cc-30fd-572f-bb4f-1f8673147195"
 QuadGK = "1fd47b50-473d-5c70-9696-f719f8f3bcdc"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 
@@ -16,6 +17,7 @@ EllipsisNotation = "1"
 QuadGK = "2.9"
 Random = "1.10.0"
 julia = "1.6"
+MPI = "0.20.22"
 
 [extras]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"

docs/src/documentation.md

@@ -56,3 +56,8 @@ Modules = [TensorCrossInterpolation]
 Pages = ["cachedfunction.jl", "batcheval.jl", "util.jl", "globalsearch.jl"]
 ```
 
+## Parallel utility
+```@autodocs
+Modules = [TensorCrossInterpolation]
+Pages = ["mpi.jl"]
+```

src/TensorCrossInterpolation.jl

@@ -3,8 +3,10 @@ module TensorCrossInterpolation
 using LinearAlgebra
 using EllipsisNotation
 using BitIntegers
-import QuadGK
+using MPI
+using Base.Threads
 
+import QuadGK
 # To add a method for rank(tci)
 import LinearAlgebra: rank, diag
 import LinearAlgebra as LA
@@ -40,5 +42,6 @@ include("conversion.jl")
 include("integration.jl")
 include("contraction.jl")
 include("globalsearch.jl")
+include("mpi.jl")
 
 end

src/abstracttensortrain.jl

@@ -131,6 +131,26 @@ function evaluate(
     return only(prod(T[:, i, :] for (T, i) in zip(tt, indexset)))
 end
 
+"""
+    function evaluate(
+        tt::TensorTrain{V},
+        indexset::Union{AbstractVector{LocalIndex}, NTuple{N, LocalIndex}}
+    )::V where {N, V}
+
+Evaluates the tensor train `tt` at indices given by `indexset` and `jndexset`. This is ment to be used for MPOs.
+"""
+function evaluate(
+    tt::AbstractTensorTrain{V},
+    indexset::Union{AbstractVector{LocalIndex},NTuple{N,LocalIndex}},
+    jndexset::Union{AbstractVector{LocalIndex},NTuple{N,LocalIndex}}
+)::V where {N,V}
+    if length(indexset) != length(tt)
+        throw(ArgumentError("To evaluate a tt of length $(length(tt)), you have to provide $(length(tt)) indices, but there were $(length(indexset))."))
+    end
+    return only(prod(T[:, i, j, :] for (T, i, j) in zip(tt, indexset, jndexset)))
+end
+
+
 """
     function evaluate(tt::TensorTrain{V}, indexset::CartesianIndex) where {V}
 
@@ -175,6 +195,38 @@ function sum(tt::AbstractTensorTrain{V}) where {V}
     return only(v)
 end
 
+"""
+    function average(tt::TensorTrain{V}) where {V}
+
+Evaluates the average of the tensor train approximation over all lattice sites in an efficient
+factorized manner.
+"""
+function average(tt::AbstractTensorTrain{V}) where {V}
+    v = transpose(sum(tt[1], dims=(1, 2))[1, 1, :]) / length(tt[1][1, :, 1])
+    for T in tt[2:end]
+        v *= sum(T, dims=2)[:, 1, :] / length(T[1, :, 1])
+    end
+    return only(v)
+end
+
+"""
+    function weightedsum(tt::TensorTrain{V}, w::Vector{V}) where {V}
+
+Evaluates the weighted sum of the tensor train approximation over all lattice sites in an efficient
+factorized manner, where w is the vector of vector of weights which has the same length and the same sizes as tt.
+"""
+function weightedsum(tt::AbstractTensorTrain{V}, w::Vector{Vector{V}}) where {V}
+    length(tt) == length(w) || throw(DimensionMismatch("The length of the Tensor Train is different from the one of the weight vector ($(length(tt)) and $(length(w)))."))
+    size(tt[1])[2] == length(w[1]) || throw(DimensionMismatch("The dimension at site 1 of the Tensor Train is different from the one of the weight vector ($(size(tt[1])[2]) and $(length(w[1])))."))
+    v = transpose(sum(tt[1].*w[1]', dims=(1, 2))[1, 1, :])
+    for i in 2:length(tt)
+        size(tt[i])[2] == length(w[i]) || throw(DimensionMismatch("The dimension at site $(i) of the Tensor Train is different from the one of the weight vector ($(size(tt[i])[2]) and $(length(w[i])))."))
+        v *= sum(tt[i].*w[i]', dims=2)[:, 1, :]
+    end
+    return only(v)
+end
+
+
 function _addtttensor(
     A::Array{V}, B::Array{V};
     factorA=one(V), factorB=one(V),
@@ -215,7 +267,7 @@ See also: [`+`](@ref)
 function add(
     lhs::AbstractTensorTrain{V}, rhs::AbstractTensorTrain{V};
     factorlhs=one(V), factorrhs=one(V),
-    tolerance::Float64=0.0, maxbonddim::Int=typemax(Int)
+    tolerance::Float64=0.0, maxbonddim::Int=typemax(Int), normalizeerror::Bool=true
 ) where {V}
     if length(lhs) != length(rhs)
         throw(DimensionMismatch("Two tensor trains with different length ($(length(lhs)) and $(length(rhs))) cannot be added elementwise."))
@@ -233,7 +285,7 @@ function add(
             for ell in 1:L
         ]
     )
-    compress!(tt, :SVD; tolerance, maxbonddim)
+    compress!(tt, :SVD; tolerance, maxbonddim, normalizeerror)
     return tt
 end
 
@@ -247,9 +299,9 @@ Subtract two tensor trains `lhs` and `rhs`. See [`add`](@ref).
 """
 function subtract(
     lhs::AbstractTensorTrain{V}, rhs::AbstractTensorTrain{V};
-    tolerance::Float64=0.0, maxbonddim::Int=typemax(Int)
+    tolerance::Float64=0.0, maxbonddim::Int=typemax(Int), normalizeerror::Bool=true
 ) where {V}
-    return add(lhs, rhs; factorrhs=-1 * one(V), tolerance, maxbonddim)
+    return add(lhs, rhs; factorrhs=-1 * one(V), tolerance, maxbonddim, normalizeerror)
 end
 
 @doc raw"""
@@ -270,6 +322,174 @@ function Base.:-(lhs::AbstractTensorTrain{V}, rhs::AbstractTensorTrain{V}) where
     return subtract(lhs, rhs)
 end
 
+function leftcanonicalize!(tt::AbstractTensorTrain{ValueType}) where {ValueType}
+    n = length(tt)  # Number of sites
+    for i in 1:n-1
+        Q, R = qr(reshape(tt[i], prod(size(tt[i])[1:end-1]), size(tt[i])[end]))
+        Q = Matrix(Q)
+
+        tt[i] = reshape(Q, size(tt[i])[1:end-1]..., size(Q, 2))  # New bond dimension after Q
+
+        tmptt = reshape(tt[i+1], size(R, 2), :)  # Reshape next tensor
+        tmptt .= Matrix(R) * tmptt
+        tt[i+1] = reshape(tmptt, size(tt[i+1])...)  # Reshape back
+    end
+end
+
+# This creates a TensorTrain which has every site right-canonical except the last
+function rightcanonicalize!(tt::AbstractTensorTrain{ValueType}) where {ValueType}
+    n = length(tt)  # Number of sites
+    for i in n:-1:2
+        # Reshape W_i into a matrix (merging right bond and physical indices)
+        W = tt[i]
+        χl, d1, d2, χr = size(W)
+        W_mat = reshape(W, χl, d1*d2*χr)
+
+        # Perform RQ decottsition: W_mat = R * Q
+        F = lq(reverse(W_mat, dims=1))
+        R, Q = reverse(F.L), reverse(Matrix(F.Q), dims=1) # https://discourse.julialang.org/t/rq-decomposition/112795/13
+
+        # Reshape Q back into the MPO tensor
+        tt[i] = reshape(Q, size(Q, 1), d1, d2, χr)  # New bond dimension after Q
+
+        # Update the previous tt tensor by absorbing R
+        tmptt = reshape(tt[i-1], :, size(R, 1))  # Reshape previous tensor
+        tmptt .= tmptt * Matrix(R)
+        tt[i-1] = reshape(tmptt, size(tt[i-1], 1), d1, d2, size(tt[i-1], 4))  # Reshape back
+    end
+end
+
+
+function centercanonicalize!(tt::Vector{Array{ValueType, N}}, center::Int; old_center::Int=0) where {ValueType, N}
+    orthogonality = checkorthogonality(tt)
+    n = length(tt)  # Number of sites
+
+    if count(==( :N ), orthogonality) == 1
+        old_center_ = findfirst(==( :N ), orthogonality)
+        if old_center_ == nothing # Useless, but help JET compiling
+            old_center_ = old_center 
+        end
+        # println("Sto canonicalizzando centrando in $center. ho trovato il centro in $old_center_. Quindi flipperò: $(center < old_center_ ? [size(tt[i]) for i in center:old_center_] : [size(tt[i]) for i in old_center_:center])")
+        if old_center != 0 && old_center != old_center_
+            println("Warning! In centercanonicalize!() old_center has been set as $old_center, but the real old center is $old_center_")
+        end
+    elseif old_center == 0
+        old_center_ = 1
+    else
+        old_center_ = old_center
+    end
+    # LEFT
+    for i in old_center_:center-1
+        Q, R = qr(reshape(tt[i], prod(size(tt[i])[1:end-1]), size(tt[i])[end]))
+        Q = Matrix(Q)
+
+        tt[i] = reshape(Q, size(tt[i])[1:end-1]..., size(Q, 2))  # New bond dimension after Q
+
+        tmptt = reshape(tt[i+1], size(R, 2), :)  # Reshape next tensor
+        tmptt = Matrix(R) * tmptt
+        tt[i+1] = reshape(tmptt, size(tt[i+1])...)  # Reshape back
+    end
+    # RIGHT
+    if count(==( :N ), orthogonality) == 1
+        old_center_ = findfirst(==( :N ), orthogonality)
+        if old_center_ == nothing # Useless, but help JET compiling
+            old_center_ = old_center 
+        end
+        if old_center != 0 && old_center != old_center_
+            println("Warning! In centercanonicalize!() old_center has been set as $old_center, but the real old center is $old_center_")
+        end
+    elseif old_center == 0
+        old_center_ = n
+    else
+        old_center_ = old_center
+    end
+    for i in old_center_:-1:center+1
+        W = tt[i]
+        χl, d1, d2, χr = size(W)
+        W_mat = reshape(W, χl, d1*d2*χr)
+
+        L, Q = lq(W_mat)
+        Q = Matrix(Q)
+        # Reshape Q back into the tt tensor
+        tt[i] = reshape(Q, size(Q, 1), d1, d2, χr)  # New bond dimension after Q
+
+        # Update the previous tt tensor by absorbing L
+        tmptt = reshape(tt[i-1], :, size(L, 1))  # Reshape previous tensor
+        tmptt = tmptt * Matrix(L)
+        tt[i-1] = reshape(tmptt, size(tt[i-1], 1), d1, d2, size(tmptt, 2))  # Reshape back
+    end
+end
+
+function move_center_right!(tt, i)
+    A = tt[i]
+    d = size(A)
+    A_mat = reshape(A, prod(d[1:end-1]), d[end])
+    Q, R = qr(A_mat)
+    Q = Matrix(Q)
+    tt[i] = reshape(Q, d[1:end-1]..., size(Q, 2))
+
+    B = tt[i+1]
+    B_mat = reshape(B, size(R, 2), :)
+    B_mat .= Matrix(R) * B_mat
+    tt[i+1] = reshape(B_mat, size(B)...)
+end
+
+function move_center_left!(tt, i)
+    A = tt[i]
+    d = size(A)
+    A_mat = reshape(A, d[1], prod(d[2:end]))
+    L, Q = lq(A_mat)
+    Q = Matrix(Q)
+    tt[i] = reshape(Q, size(Q,1), d[2:end]...)
+
+    B = tt[i-1]
+    B_mat = reshape(B, :, size(L,1))
+    B_mat .= B_mat * Matrix(L)
+    tt[i-1] = reshape(B_mat, size(B)[1:3]..., size(L,1))
+end
+
+
+function leftcanonicalize(tt::AbstractTensorTrain{ValueType}) where {ValueType}
+    tt_ = deepcopy(tt)
+    leftcanonicalize!(tt_)
+    return tt_
+end
+
+# This creates a TensorTrain which has every site right-canonical except the last
+function rightcanonicalize(tt::AbstractTensorTrain{ValueType}) where {ValueType}
+    tt_ = deepcopy(tt)
+    rightcanonicalize!(tt_)
+    return tt_
+end
+
+# This creates a TensorTrain which has every site right-canonical except the last
+function centercanonicalize(tt::Vector{Array{ValueType, N}}, center::Int; old_center::Int=0) where {ValueType, N}
+    tt_ = deepcopy(tt)
+    centercanonicalize!(tt_, center; old_center)
+    return tt_
+end
+
+function checkorthogonality(tt::Vector{Array{ValueType, N}}) where {ValueType, N}
+    ort = Vector{Symbol}(undef, length(tt))
+    for i in 1:length(tt)
+        W = tt[i]
+        left_check = _contract(permutedims(W, (4,2,3,1,)), W, (2,3,4,),(2,3,1))
+        right_check = _contract(W, permutedims(W, (4,2,3,1,)), (2,3,4,),(2,3,1))
+        is_left = isapprox(left_check, I, atol=1e-7)
+        is_right = isapprox(right_check, I, atol=1e-7)
+        ort[i] = if is_left && is_right
+            :O # Orthogonal
+        elseif is_left
+            :L # Left orthogonal
+        elseif is_right
+            :R # Right orthogonal
+        else
+            :N # Non orthogonal
+        end
+    end
+    return ort
+end
+
 """
 Squared Frobenius norm of a tensor train.
 """