Change bond_tensor return order

Author: Yue-Zhengyuan

src/algorithms/time_evolution/ntupdate3site.jl

@@ -54,8 +54,8 @@ function _bond_truncate(
     A, B = state2[row, col], state2[row, cp1]
 
     # create bond environment
-    X, a = bond_tensor_first(A; trunc = trunctol(; rtol = 1.0e-12))
-    Y, b = bond_tensor_last(B; trunc = trunctol(; rtol = 1.0e-12))
+    a, X = bond_tensor_first(A; trunc = trunctol(; rtol = 1.0e-12))
+    b, Y = bond_tensor_last(B; trunc = trunctol(; rtol = 1.0e-12))
     benv = bondenv_ntu(row, col, X, Y, state2, alg.bondenv_alg)
     @debug "cond(benv) before gauge fix: $(LinearAlgebra.cond(benv))"
     if alg.fixgauge
@@ -76,8 +76,8 @@ function _bond_truncate(
     end
 
     a, s, b, info = bond_truncate(a, b, benv, alg.opt_alg)
-    A = undo_bond_tensor_first(X, a)
-    B = undo_bond_tensor_last(Y, b)
+    A = undo_bond_tensor_first(a, X)
+    B = undo_bond_tensor_last(b, Y)
     normalize!(A, Inf)
     normalize!(B, Inf)
     normalize!(s, Inf)

src/algorithms/time_evolution/simpleupdate.jl

@@ -113,12 +113,12 @@ function _su_iter!(
     ϵ, s = 0.0, nothing
     gate_axs = alg.purified ? (1:1) : (1:2)
     for gate_ax in gate_axs
-        X, a = bond_tensor_first(A; gate_ax, positive = true)
-        Y, b = bond_tensor_last(B; gate_ax, positive = true)
+        a, X = bond_tensor_first(A; gate_ax, positive = true)
+        b, Y = bond_tensor_last(B; gate_ax, positive = true)
         a, s, b, ϵ′ = _apply_gate(a, b, gate, trunc)
         ϵ = max(ϵ, ϵ′)
-        A = undo_bond_tensor_first(X, a; gate_ax)
-        B = undo_bond_tensor_last(Y, b; gate_ax)
+        A = undo_bond_tensor_first(a, X; gate_ax)
+        B = undo_bond_tensor_last(b, Y; gate_ax)
     end
     # rotate back
     A = _bond_rotation(A, bond[1], rev; inv = true)

src/algorithms/truncation/bond_tensor.jl

@@ -14,19 +14,19 @@ For PEPOTensor,
 ```
     gate_ax = 1                 gate_ax = 2
 
-     1  2                           2         2      
-      ↘ |                           |          ↘     
+    1   2                           2         2
+      ↘ |                           |          ↘
     5 - X ← 3   1 ← a - 3       5 - X ← 3   1 ← a - 3
-        |            ↘              | ↘              
-        4             2             4  1             
+        |            ↘              | ↘
+        4             2             4   1
 ```
 """
 function bond_tensor_first(A::PEPSTensor; gate_ax::Integer = 1, kwargs...)
     @assert gate_ax == 1
     X, a = left_orth!(permute(A, ((2, 4, 5), (1, 3)); copy = true); kwargs...)
     X = permute(X, (1, 4, 2, 3))
     a = permute(a, ((1, 2), (3,)))
-    return X, a
+    return a, X
 end
 function bond_tensor_first(A::PEPOTensor; gate_ax::Integer = 1, kwargs...)
     @assert 1 <= gate_ax <= 2
@@ -37,17 +37,17 @@ function bond_tensor_first(A::PEPOTensor; gate_ax::Integer = 1, kwargs...)
     end
     X = permute(X, (1, 2, 5, 3, 4))
     a = permute(a, ((1, 2), (3,)))
-    return X, a
+    return a, X
 end
 
 """
 Undo the decomposition in `bond_tensor_first`.
 """
-function undo_bond_tensor_first(X::PEPSOrth, a::MPSTensor; gate_ax::Integer = 1)
+function undo_bond_tensor_first(a::MPSTensor, X::PEPSOrth; gate_ax::Integer = 1)
     @assert gate_ax == 1
     return @tensor A[-1; -2 -3 -4 -5] := X[-2 1 -4 -5] * a[1 -1 -3]
 end
-function undo_bond_tensor_first(X::PEPOOrth, a::MPSTensor; gate_ax::Integer = 1)
+function undo_bond_tensor_first(a::MPSTensor, X::PEPOOrth; gate_ax::Integer = 1)
     @assert 1 <= gate_ax <= 2
     if gate_ax == 1
         return @tensor A[-1 -2; -3 -4 -5 -6] := X[-2 -3 1 -5 -6] * a[1 -1 -4]
@@ -84,7 +84,7 @@ function bond_tensor_last(A::PEPSTensor; gate_ax::Integer = 1, kwargs...)
     Y, b = left_orth!(permute(A, ((2, 3, 4), (1, 5)); copy = true); kwargs...)
     Y = permute(Y, (1, 2, 3, 4))
     b = permute(b, ((3, 2), (1,)))
-    return Y, b
+    return b, Y
 end
 function bond_tensor_last(A::PEPOTensor; gate_ax::Integer = 1, kwargs...)
     @assert 1 <= gate_ax <= 2
@@ -95,17 +95,17 @@ function bond_tensor_last(A::PEPOTensor; gate_ax::Integer = 1, kwargs...)
     end
     Y = permute(Y, (1, 2, 3, 4, 5))
     b = permute(b, ((3, 2), (1,)))
-    return Y, b
+    return b, Y
 end
 
 """
 Undo the decomposition in `bond_tensor_last`.
 """
-function undo_bond_tensor_last(Y::PEPSOrth, b::MPSTensor; gate_ax::Integer = 1)
+function undo_bond_tensor_last(b::MPSTensor, Y::PEPSOrth; gate_ax::Integer = 1)
     @assert gate_ax == 1
     return @tensor A[-1; -2 -3 -4 -5] := b[-5 -1 1] * Y[-2 -3 -4 1]
 end
-function undo_bond_tensor_last(Y::PEPOOrth, b::MPSTensor; gate_ax::Integer = 1)
+function undo_bond_tensor_last(b::MPSTensor, Y::PEPOOrth; gate_ax::Integer = 1)
     @assert 1 <= gate_ax <= 2
     if gate_ax == 1
         return @tensor A[-1 -2; -3 -4 -5 -6] := b[-6 -1 1] * Y[-2 -3 -4 -5 1]

test/bondenv/benv_ctm.jl

@@ -42,8 +42,8 @@ function test_benv_ctm(state::Union{InfinitePEPS, InfinitePEPO})
     for row in 1:Nr, col in 1:Nc
         cp1 = PEPSKit._next(col, Nc)
         A, B = state.A[row, col], state.A[row, cp1]
-        X, a = PEPSKit.bond_tensor_first(A)
-        Y, b = PEPSKit.bond_tensor_last(B)
+        a, X = PEPSKit.bond_tensor_first(A)
+        b, Y = PEPSKit.bond_tensor_last(B)
         benv = PEPSKit.bondenv_ctm(row, col, X, Y, env)
         Z = PEPSKit.positive_approx(benv)
         # verify that gauge fixing can greatly reduce

test/bondenv/benv_ntu.jl

@@ -15,8 +15,8 @@ function test_ntu_env(
     for row in 1:Nr, col in 1:Nc
         cp1 = PEPSKit._next(col, Nc)
         A, B = state.A[row, col], state.A[row, cp1]
-        X, a = PEPSKit.bond_tensor_first(A)
-        Y, b = PEPSKit.bond_tensor_last(B)
+        a, X = PEPSKit.bond_tensor_first(A)
+        b, Y = PEPSKit.bond_tensor_last(B)
         @tensor ab[DX DY; da db] := a[DX da D] * b[D db DY]
         benv = PEPSKit.bondenv_ntu(row, col, X, Y, state, env_alg)
         # this is a result of `bond_tensor_...`