Update sweep_contract.jl

Author: chubbc

src/sweep_contract.jl

@@ -75,24 +75,45 @@ function permutebetween(from, to)
 end
 
 """
-    sweep_contract!(TN::TensorNetwork, χ, τ;
+    sweep_contract(LTN::LabelledTensorNetwork, χ, τ;
         fast=false, valid=false, planar=false, connected=false, report=false)
-    sweep_contract!(LTN::LabelledTensorNetwork, χ, τ;
+    sweep_contract(TN::TensorNetwork, χ, τ;
         fast=false, valid=false, planar=false, connected=false, report=false)
-
 Returns the contraction of the `TensorNetwork TN`, or the `LabelledTensorNetwork LTN` using
 the sweepline contraction algorithm of `arXiv:2101.04125`. The MPS is truncated down to a
 bond dimension of `χ` whenever any bond dimension exceeds `τ`.
-
 By default the network is checked for validity, planarised, and sweep-connected, where
 necessary. The keyword flags `valid`, `planar`, and `connected` can be used to skip these,
 or the flag `fast` can be used to skip them all. If these flags are enabled then contraction
 may fail on poorly formed networks.
-
 To avoid underflow/overflow issues the contraction value of the network is returned as a
 tuple `(f::Float64, i::Int64)` where `1≦f<2` or `f` is `0`, representing a value of `f*2^i`.
 The function `ldexp` can be used to convert this back to a Float64.
+`sweep_contract` is non-mutating and acts upon a deep copy of the network, where possible
+use the more efficient mutating version `sweep_contract!`.
+"""
+sweep_contract(LTN::LabelledTensorNetwork, χ::Int, τ::Int;
+    fast=false, valid=false, planar=false, connected=false, report=false) =
+sweep_contract!(deepcopy(LTN), χ, τ;
+    fast=fast, planar=planar, connected=connected, report=report)
+
+sweep_contract(TN::TensorNetwork, χ::Int, τ::Int;
+    fast=false, valid=false, planar=false, connected=false, report=false) =
+sweep_contract!(deepcopy(TN), χ, τ;
+    fast=fast, planar=planar, connected=connected, report=report)
+
 """
+    sweep_contract!(LTN::LabelledTensorNetwork, χ, τ;
+        fast=false, valid=false, planar=false, connected=false, report=false)
+    sweep_contract!(TN::TensorNetwork, χ, τ;
+        fast=false, valid=false, planar=false, connected=false, report=false)
+The mutating form of `sweep_contract`.
+"""
+sweep_contract!(LTN::LabelledTensorNetwork, χ::Int, τ::Int;
+    fast=false, valid=false, planar=false, connected=false, report=false) =
+sweep_contract!(delabel(LTN), χ, τ;
+        fast=fast, planar=planar, connected=connected, report=report)
+
 function sweep_contract!(TN::TensorNetwork, χ::Int, τ::Int;
     fast=false,valid=false,planar=false,connected=false,report=false)::Tuple{Float64,Int}
     if !fast
@@ -198,27 +219,3 @@ function sweep_contract!(TN::TensorNetwork, χ::Int, τ::Int;
     h = Int(floor(log2(abs(res))));
     return (res/exp2(h),resexp+h);
 end
-
-sweep_contract!(
-    LTN::LabelledTensorNetwork, χ::Int, τ::Int;
-    fast=false, valid=false, planar=false, connected=false, report=false
-) = sweep_contract!(
-    delabel(LTN), χ, τ;
-    fast=fast, planar=planar, connected=connected, report=report
-)
-
-sweep_contract(
-    TN::TensorNetwork, χ::Int, τ::Int;
-    fast=false, valid=false, planar=false, connected=false, report=false
-) = sweep_contract!(
-    deepcopy(TN), χ, τ;
-    fast=fast, planar=planar, connected=connected, report=report
-)
-
-sweep_contract(
-    LTN::LabelledTensorNetwork, χ::Int, τ::Int;
-    fast=false, valid=false, planar=false, connected=false, report=false
-) = sweep_contract!(
-    deepcopy(LTN), χ, τ;
-    fast=fast, planar=planar, connected=connected, report=report
-)