From 921f3628041464d65a427e670da15157e6efbfc6 Mon Sep 17 00:00:00 2001
From: Brian Dellabetta <brian-dellabetta@users.noreply.github.com>
Date: Thu, 4 Jan 2024 15:04:34 -0600
Subject: [PATCH] [ITensors] Add missing kwargs to `replacebond!` and
 downstream functions (#1300)

---
 src/mps/mps.jl                                |  7 +++
 src/tensor_operations/matrix_decomposition.jl | 46 +++++++++++++++++--
 test/ITensorLegacyMPS/base/test_mps.jl        | 15 ++++++
 3 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/src/mps/mps.jl b/src/mps/mps.jl
index 67458f07a9..a6bec60f96 100644
--- a/src/mps/mps.jl
+++ b/src/mps/mps.jl
@@ -540,7 +540,11 @@ function replacebond!(
   maxdim=nothing,
   cutoff=nothing,
   eigen_perturbation=nothing,
+  # svd kwargs
   svd_alg=nothing,
+  use_absolute_cutoff=nothing,
+  use_relative_cutoff=nothing,
+  min_blockdim=nothing,
 )
   normalize = NDTensors.replace_nothing(normalize, false)
   swapsites = NDTensors.replace_nothing(swapsites, false)
@@ -563,6 +567,9 @@ function replacebond!(
     eigen_perturbation,
     svd_alg,
     tags=tags(linkind(M, b)),
+    use_absolute_cutoff,
+    use_relative_cutoff,
+    min_blockdim,
   )
   M[b] = L
   M[b + 1] = R
diff --git a/src/tensor_operations/matrix_decomposition.jl b/src/tensor_operations/matrix_decomposition.jl
index 2ce37a4355..c288b8348d 100644
--- a/src/tensor_operations/matrix_decomposition.jl
+++ b/src/tensor_operations/matrix_decomposition.jl
@@ -600,6 +600,9 @@ function factorize_svd(
   maxdim=nothing,
   cutoff=nothing,
   tags=nothing,
+  use_absolute_cutoff=nothing,
+  use_relative_cutoff=nothing,
+  min_blockdim=nothing,
 )
   leftdir, rightdir = dir, dir
   if !isnothing(leftdir)
@@ -619,6 +622,9 @@ function factorize_svd(
     cutoff,
     lefttags=tags,
     righttags=tags,
+    use_absolute_cutoff,
+    use_relative_cutoff,
+    min_blockdim,
   )
   if isnothing(USV)
     return nothing
@@ -651,6 +657,8 @@ function factorize_eigen(
   maxdim=nothing,
   cutoff=nothing,
   tags=nothing,
+  use_absolute_cutoff=nothing,
+  use_relative_cutoff=nothing,
 )
   if ortho == "left"
     Lis = commoninds(A, indices(Linds...))
@@ -669,7 +677,18 @@ function factorize_eigen(
     delta_A2 = noprime(delta_A2)
     A2 += delta_A2
   end
-  F = eigen(A2, Lis, simLis; ishermitian=true, mindim, maxdim, cutoff, tags)
+  F = eigen(
+    A2,
+    Lis,
+    simLis;
+    ishermitian=true,
+    mindim,
+    maxdim,
+    cutoff,
+    tags,
+    use_absolute_cutoff,
+    use_relative_cutoff,
+  )
   D, _, spec = F
   L = F.Vt
   R = dag(L) * A
@@ -780,7 +799,19 @@ function factorize(
   end
   if which_decomp == "svd"
     LR = factorize_svd(
-      A, Linds...; mindim, maxdim, cutoff, tags, ortho, alg=svd_alg, dir, singular_values!
+      A,
+      Linds...;
+      mindim,
+      maxdim,
+      cutoff,
+      tags,
+      ortho,
+      alg=svd_alg,
+      dir,
+      singular_values!,
+      use_absolute_cutoff,
+      use_relative_cutoff,
+      min_blockdim,
     )
     if isnothing(LR)
       return nothing
@@ -788,7 +819,16 @@ function factorize(
     L, R, spec = LR
   elseif which_decomp == "eigen"
     L, R, spec = factorize_eigen(
-      A, Linds...; mindim, maxdim, cutoff, tags, ortho, eigen_perturbation
+      A,
+      Linds...;
+      mindim,
+      maxdim,
+      cutoff,
+      tags,
+      ortho,
+      eigen_perturbation,
+      use_absolute_cutoff,
+      use_relative_cutoff,
     )
   elseif which_decomp == "qr"
     L, R = factorize_qr(A, Linds...; ortho, tags)
diff --git a/test/ITensorLegacyMPS/base/test_mps.jl b/test/ITensorLegacyMPS/base/test_mps.jl
index f2a3e73e1e..d7fa17b696 100644
--- a/test/ITensorLegacyMPS/base/test_mps.jl
+++ b/test/ITensorLegacyMPS/base/test_mps.jl
@@ -621,6 +621,21 @@ include(joinpath(@__DIR__, "utils", "util.jl"))
     replacebond!(psi, 5, phi; ortho="left")
     @test ITensors.leftlim(psi) == 3
     @test ITensors.rightlim(psi) == 7
+
+    # check that replacebond! runs with svd kwargs
+    psi = randomMPS(sites)
+    phi = psi[1] * psi[2]
+    replacebond!(psi, 1, phi; ortho="left", which_decomp="svd", use_relative_cutoff=true)
+    phi = psi[5] * psi[6]
+    replacebond!(
+      psi,
+      5,
+      phi;
+      ortho="right",
+      which_decomp="svd",
+      use_absolute_cutoff=true,
+      min_blockdim=2,
+    )
   end
 end