[WIP] Implement styles in a top-to-bottom approach by AFeuerpfeil · Pull Request #360 · QuantumKitHub/MPSKit.jl

AFeuerpfeil · 2025-12-02T20:32:14Z

I am currently working on getting the algorithms to run for user-defined AbstractMPS types.
To this end, I will go through the algorithms (currently focussing on IDMRG and VUMPS) and implement the Style interface for the highest-level functions, which are called in these algorithms.

Examples for these are calc_galerkin, expectation_value, environments, recalculate!, (A)C(2)_hamiltonian, transfer_leftenv!, transfer_rightenv!.

github-actions · 2025-12-02T20:43:08Z

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diff --git a/src/algorithms/derivatives/hamiltonian_derivatives.jl b/src/algorithms/derivatives/hamiltonian_derivatives.jl
index da6717e..bf1407e 100644
--- a/src/algorithms/derivatives/hamiltonian_derivatives.jl
+++ b/src/algorithms/derivatives/hamiltonian_derivatives.jl
@@ -69,7 +69,8 @@ end
 
 # Constructors
 # ------------
-function AC_hamiltonian(::GeometryStyle, ::HamiltonianStyle,
+function AC_hamiltonian(
+        ::GeometryStyle, ::HamiltonianStyle,
         site::Int, below, operator, above, envs
     )
     GL = leftenv(envs, site, below)
@@ -140,7 +141,8 @@ function AC_hamiltonian(::GeometryStyle, ::HamiltonianStyle,
     )
 end
 
-function AC2_hamiltonian(::GeometryStyle, ::HamiltonianStyle,
+function AC2_hamiltonian(
+        ::GeometryStyle, ::HamiltonianStyle,
         site::Int, below, operator, above, envs
     )
     GL = leftenv(envs, site, below)
diff --git a/src/algorithms/derivatives/mpo_derivatives.jl b/src/algorithms/derivatives/mpo_derivatives.jl
index 6dc9fbd..d7bae10 100644
--- a/src/algorithms/derivatives/mpo_derivatives.jl
+++ b/src/algorithms/derivatives/mpo_derivatives.jl
@@ -23,8 +23,10 @@ MPO_AC2_Hamiltonian(GL, O1, O2, GR) = MPODerivativeOperator(GL, (O1, O2), GR)
 # Constructors
 # ------------
 function C_hamiltonian(site::Int, below, operator, above, envs)
-    return C_hamiltonian(GeometryStyle(below, operator, above), OperatorStyle(operator), 
-        site, below, operator, above, envs)
+    return C_hamiltonian(
+        GeometryStyle(below, operator, above), OperatorStyle(operator),
+        site, below, operator, above, envs
+    )
 end
 function C_hamiltonian(::GeometryStyle, ::OperatorStyle, site::Int, below, operator, above, envs)
     return MPO_C_Hamiltonian(leftenv(envs, site + 1, below), rightenv(envs, site, below))
diff --git a/src/algorithms/expval.jl b/src/algorithms/expval.jl
index 17d74f9..ce8e424 100644
--- a/src/algorithms/expval.jl
+++ b/src/algorithms/expval.jl
@@ -121,13 +121,15 @@ function contract_mpo_expval2(
         τ[3 4; 9 10] * A1[8 1 2; 5] * A2[5 7 13; 14] * O[10 12; 6 7]
 end
 
-function expectation_value(::FiniteChainStyle, ::HamiltonianStyle,
+function expectation_value(
+        ::FiniteChainStyle, ::HamiltonianStyle,
         ψ, H, envs = environments(ψ, H)
     )
     return dot(ψ, H, ψ, envs) / dot(ψ, ψ)
 end
 
-function expectation_value(::InfiniteChainStyle, ::HamiltonianStyle,
+function expectation_value(
+        ::InfiniteChainStyle, ::HamiltonianStyle,
         ψ, H, envs = environments(ψ, H)
     )
     return sum(1:length(ψ)) do i
@@ -148,7 +150,8 @@ end
 function expectation_value(::InfiniteChainStyle, ::MPOStyle, ψ, mpo, envs...)
     return expectation_value(convert(MultilineMPS, ψ), convert(MultilineMPO, mpo), envs...)
 end
-function expectation_value(::InfiniteChainStyle, ::MPOStyle,
+function expectation_value(
+        ::InfiniteChainStyle, ::MPOStyle,
         ψ::Multiline, O::Multiline,
         envs::MultilineEnvironments = environments(ψ, O)
     )
diff --git a/src/algorithms/toolbox.jl b/src/algorithms/toolbox.jl
index ed4a6a1..2e54341 100644
--- a/src/algorithms/toolbox.jl
+++ b/src/algorithms/toolbox.jl
@@ -91,7 +91,7 @@ function transfer_spectrum(above::AbstractMPS; kwargs...)
     return transfer_spectrum(GeometryStyle(above), above; kwargs...)
 end
 function transfer_spectrum(
-        ::InfiniteChainStyle, above::AbstractMPS; 
+        ::InfiniteChainStyle, above::AbstractMPS;
         below = above, tol = Defaults.tol, num_vals = 20,
         sector = first(sectors(oneunit(left_virtualspace(above, 1))))
     )
@@ -214,7 +214,8 @@ function variance(state::AbstractMPS, H::AbstractMPO, envs = environments(state,
     return variance(GeometryStyle(state, H), OperatorStyle(H), state, H, envs)
 end
 
-function variance(::InfiniteChainStyle, ::HamiltonianStyle,
+function variance(
+        ::InfiniteChainStyle, ::HamiltonianStyle,
         state::AbstractMPS, H::AbstractMPO, envs = environments(state, H)
     )
     e_local = map(1:length(state)) do i
@@ -229,7 +230,8 @@ function variance(::InfiniteChainStyle, ::HamiltonianStyle,
     return real(expectation_value(state, (H - H_renormalized)^2))
 end
 
-function variance(::FiniteChainStyle, ::HamiltonianStyle,
+function variance(
+        ::FiniteChainStyle, ::HamiltonianStyle,
         state::AbstractMPS, H::AbstractMPO, envs = environments(state, H)
     )
     H2 = H * H
diff --git a/src/environments/abstract_envs.jl b/src/environments/abstract_envs.jl
index 17b9fd9..718e71a 100644
--- a/src/environments/abstract_envs.jl
+++ b/src/environments/abstract_envs.jl
@@ -69,15 +69,17 @@ end
 Determine an appropriate algorithm for computing the environments, based on the given `kwargs...`.
 """
 function environment_alg(below::AbstractMPS, operator::AbstractMPO, above::AbstractMPS; kwargs...)
-    return environment_alg(GeometryStyle(below, operator, above), OperatorStyle(operator), 
-        below, operator, above; kwargs...)
+    return environment_alg(
+        GeometryStyle(below, operator, above), OperatorStyle(operator),
+        below, operator, above; kwargs...
+    )
 end
 
 function environment_alg(
         ::InfiniteChainStyle, ::MPOStyle, ::AbstractMPS, ::AbstractMPO, ::AbstractMPS;
         tol = Defaults.tol, maxiter = Defaults.maxiter, krylovdim = Defaults.krylovdim,
         verbosity = Defaults.VERBOSE_NONE, eager = true
-    ) 
+    )
     # TODO: Wouldn't it be simpler to use Arnoldi(; eager=eager, verbosity = verbosity, kwargs...)? (Same for the other ones)
     return Arnoldi(; tol, maxiter, krylovdim, verbosity, eager)
 end
@@ -121,8 +123,9 @@ function leftenv(ca::AbstractMPSEnvironments, ind, state::AbstractMPS)
     return leftenv(GeometryStyle(ca, state), ca, ind, state)
 end
 
-function recalculate!(envs::AbstractMPSEnvironments,
-        below::AbstractMPS,  operator::AbstractMPO, above::AbstractMPS;
+function recalculate!(
+        envs::AbstractMPSEnvironments,
+        below::AbstractMPS, operator::AbstractMPO, above::AbstractMPS;
         kwargs...
     )
     return recalculate!(
diff --git a/src/environments/infinite_envs.jl b/src/environments/infinite_envs.jl
index 532a858..275eaf1 100644
--- a/src/environments/infinite_envs.jl
+++ b/src/environments/infinite_envs.jl
@@ -28,11 +28,12 @@ function environments(
     return recalculate!(envs, below, operator, above; kwargs...)
 end
 
-function issamespace(envs::AbstractMPSEnvironments,
+function issamespace(
+        envs::AbstractMPSEnvironments,
         below::AbstractMPS, operator::AbstractMPO, above::AbstractMPS
     )
     return issamespace(
-        GeometryStyle(envs, below, operator, above), OperatorStyle(operator), 
+        GeometryStyle(envs, below, operator, above), OperatorStyle(operator),
         envs, below, operator, above
     )
 end
@@ -56,7 +57,8 @@ function issamespace(
     return true
 end
 
-function recalculate!(::InfiniteChainStyle, ::OperatorStyle,
+function recalculate!(
+        ::InfiniteChainStyle, ::OperatorStyle,
         envs::AbstractMPSEnvironments, below::AbstractMPS,
         operator::AbstractMPO,
         above::AbstractMPS = below;
@@ -86,7 +88,7 @@ function initialize_environments(
         below::AbstractMPS, operator::AbstractMPO, above::AbstractMPS = below
     )
     return initialize_environments(
-        GeometryStyle(below, operator, above), OperatorStyle(operator), 
+        GeometryStyle(below, operator, above), OperatorStyle(operator),
         below, operator, above
     )
 end
@@ -105,12 +107,13 @@ function compute_leftenvs!(
         operator::AbstractMPO, above::AbstractMPS, alg
     )
     return compute_leftenvs!(
-        GeometryStyle(envs, below, operator, above), OperatorStyle(operator), 
+        GeometryStyle(envs, below, operator, above), OperatorStyle(operator),
         envs, below, operator, above, alg
     )
 end
 
-function compute_leftenvs!(::InfiniteChainStyle, ::MPOStyle,
+function compute_leftenvs!(
+        ::InfiniteChainStyle, ::MPOStyle,
         envs::AbstractMPSEnvironments, below::AbstractMPS,
         operator::AbstractMPO, above::AbstractMPS, alg
     )
@@ -130,12 +133,13 @@ function compute_rightenvs!(
         operator::AbstractMPO, above::AbstractMPS, alg
     )
     return compute_rightenvs!(
-        GeometryStyle(envs, below, operator, above), OperatorStyle(operator), 
+        GeometryStyle(envs, below, operator, above), OperatorStyle(operator),
         envs, below, operator, above, alg
     )
 end
 
-function compute_rightenvs!(::InfiniteChainStyle, ::MPOStyle,
+function compute_rightenvs!(
+        ::InfiniteChainStyle, ::MPOStyle,
         envs::AbstractMPSEnvironments, below::AbstractMPS,
         operator::AbstractMPO, above::AbstractMPS, alg
     )
@@ -158,7 +162,8 @@ end
 # this avoids catastrophic blow-up of norms, while keeping the total normalized
 # and does not lead to issues for negative overlaps and real entries.
 
-function TensorKit.normalize!(::InfiniteChainStyle, ::MPOStyle,
+function TensorKit.normalize!(
+        ::InfiniteChainStyle, ::MPOStyle,
         envs::AbstractMPSEnvironments, below, operator, above
     )
     for i in 1:length(operator)
@@ -172,7 +177,8 @@ end
 
 # InfiniteMPOHamiltonian environments
 # -----------------------------------
-function initialize_environments(::InfiniteChainStyle, ::HamiltonianStyle,
+function initialize_environments(
+        ::InfiniteChainStyle, ::HamiltonianStyle,
         below, operator, above = below
     )
     L = check_length(above, operator, below)
@@ -202,7 +208,8 @@ function initialize_environments(::InfiniteChainStyle, ::HamiltonianStyle,
     return GLs, GRs
 end
 
-function compute_leftenvs!(::InfiniteChainStyle, ::HamiltonianStyle,
+function compute_leftenvs!(
+        ::InfiniteChainStyle, ::HamiltonianStyle,
         envs, below, operator, above, alg
     )
     L = check_length(below, above, operator)
@@ -260,8 +267,10 @@ function left_cyclethrough!(
         index::Int, GL, below::AbstractMPS, operator::AbstractMPO,
         above::AbstractMPS = below
     )
-    return left_cyclethrough!(GeometryStyle(below, operator, above), OperatorStyle(operator), index, GL,
-        below, operator, above)
+    return left_cyclethrough!(
+        GeometryStyle(below, operator, above), OperatorStyle(operator), index, GL,
+        below, operator, above
+    )
 end
 function left_cyclethrough!(
         ::InfiniteChainStyle, ::HamiltonianStyle,
@@ -339,7 +348,7 @@ function right_cyclethrough!(
         above::AbstractMPS = below
     )
     return right_cyclethrough!(
-        GeometryStyle(below, operator, above), OperatorStyle(operator), 
+        GeometryStyle(below, operator, above), OperatorStyle(operator),
         index, GR, below, operator, above
     )
 end
@@ -371,7 +380,8 @@ function transfer_leftenv!(
         envs::AbstractMPSEnvironments, below::AbstractMPS,
         operator::AbstractMPO, above::AbstractMPS, site::Int
     )
-    return transfer_leftenv!(GeometryStyle(envs, below, operator, above), OperatorStyle(operator), 
+    return transfer_leftenv!(
+        GeometryStyle(envs, below, operator, above), OperatorStyle(operator),
         envs, below, operator, above, site
     )
 end
@@ -388,7 +398,8 @@ function transfer_rightenv!(
         envs::AbstractMPSEnvironments, below::AbstractMPS,
         operator::AbstractMPO, above::AbstractMPS, site::Int
     )
-    return transfer_rightenv!(GeometryStyle(envs, below, operator, above), OperatorStyle(operator), 
+    return transfer_rightenv!(
+        GeometryStyle(envs, below, operator, above), OperatorStyle(operator),
         envs, below, operator, above, site
     )
 end

codecov · 2025-12-02T20:47:56Z

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/operators/lazysum.jl	50.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
src/algorithms/groundstate/find_groundstate.jl	`76.92% <100.00%> (ø)`
src/algorithms/groundstate/idmrg.jl	`100.00% <100.00%> (ø)`
src/algorithms/groundstate/vumps.jl	`85.91% <100.00%> (+0.20%)`	⬆️
src/operators/lazysum.jl	`70.37% <50.00%> (-1.63%)`	⬇️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

lkdvos

This looks great, I really like that we can relax the input types.

AFeuerpfeil · 2025-12-05T23:24:30Z

It definitely feels like it is going in the right direction.
In my current fork, it is not reducing the size of the code but is also not adding too much boilerplate.
One question I came up with is the following:
Do we at all want to restrict input types to AbstractMPS, AbstractMPO, AbstractMPSEnvironments or just leave that completely open to the user?
And if we want to restrict it, then at which level, only at the topmost function, which dispatches onto the function defined on Styles or in all levels?

An example, how the restriction only for the topmost function in the call tree looks like, is

function environments(above::AbstractMPS, op::AbstractMPO, below::AbstractMPS)
    return environments(GeometryStyle(above, op, below), OperatorStyle(op), above, op, below)
end

and then

function environments(::InfiniteChainStyle, ::HamiltonianStyle, above, op, below)
 ...
end

AFeuerpfeil added 2 commits December 2, 2025 15:27

start adaptation of algorithms to styles

1082142

fix logic

d45f42e

AFeuerpfeil added 2 commits December 4, 2025 16:07

fix test failes due to LazySum

a4f2ec8

fix formatting and misspelling in last commit

3d1f6c0

lkdvos reviewed Dec 5, 2025

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[WIP] Implement styles in a top-to-bottom approach#360

[WIP] Implement styles in a top-to-bottom approach#360
AFeuerpfeil wants to merge 5 commits intoQuantumKitHub:mainfrom
AFeuerpfeil:pr-styles-algorithms

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