Wolfram Language Paclet Repository
Community-contributed installable additions to the Wolfram Language
Wolfram`TensorNetworks`
TensorNetworkFreeIndices  |
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Examples
(5)
Scope
(3)
Explicit index lists
(1)
Apply directly to a list of per-tensor index lists, bypassing the TensorNetwork object:
In[1]:=
 | TensorNetworkFreeIndices |
Out[1]=
{1,3}
Indices may be symbols rather than integers; the same count rule applies:
In[2]:=
| TensorNetworkFreeIndices |
Out[2]=
{a,c,d}
Here the label appears in three tensors, so it is contracted (a hyperedge) and is excluded from the result.
b
Graph form
(1)
Periodic boundary
(1)
Applications
(1)
Properties & Relations
(1)
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Get the uncontracted (free) indices in a tensor network:
In[1]:=
tn=
[{RandomReal[{-1,1},{2,3}],RandomReal[{-1,1},{3,4}]},{{i,j},{j,k}}];
 | TensorNetwork |
In[2]:=
| TensorNetworkFreeIndices |
Out[2]=
{i,k}
A fully contracted network has no free indices:
In[3]:=
| TensorNetworkFreeIndices |
 | TensorNetwork |
Out[3]=
{}
For an open-boundary matrix product state, the free indices are the physical legs at each site:
In[4]:=
SeedRandom[42];mps=
["MPS"[4,2,2]];
[mps]
| RandomTensorNetwork |
| TensorNetworkFreeIndices |
Out[4]=
{5,6,7,8}
""