修改库

.venv/lib/python3.12/site-packages/qtealeaves/tooling/permutations.py

@@ -0,0 +1,55 @@
+# This code is part of qtealeaves.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""
+Common permutations often used in tensor network methods.
+"""
+from functools import lru_cache
+
+__all__ = []
+
+
+@lru_cache(maxsize=None)
+def _transpose_idx1(num_legs, contracted_idx):
+    """Move second last index instead of last in `_transpose_idx`."""
+    return _transpose_idx(num_legs - 1, contracted_idx) + (num_legs - 1,)
+
+
+@lru_cache(maxsize=None)
+def _transpose_idx2(num_legs, contracted_idx):
+    """Move third last index instead of last in `_transpose_idx`."""
+    return _transpose_idx(num_legs - 2, contracted_idx) + (
+        num_legs - 2,
+        num_legs - 1,
+    )
+
+
+@lru_cache(maxsize=None)
+def _transpose_idx(num_legs, contracted_idx):
+    """
+    Transpose in the original order the indexes
+    of a n-legs tensor contracted over the
+    index `contracted_idx`
+
+    Parameters
+    ----------
+    contracted_idx : int
+        Index over which there has been a contraction
+
+    Returns
+    -------
+    tuple
+        Indexes for the transposition
+    """
+    if contracted_idx > num_legs - 1:
+        raise ValueError(
+            f"Cannot contract leg {contracted_idx} of tensor with {num_legs} legs"
+        )
+    return (*range(contracted_idx), num_legs - 1, *range(contracted_idx, num_legs - 1))