abstract some SU related functionality (for block/fermionic)

docs/changelog.md

@@ -3,7 +3,7 @@
 Release notes for `quimb`.
 
 (whats-new-1-8-2)=
-## v1.8.2 (unreleased)
+## v1.8.2 (2024-06-12)
 
 **Enhancements:**
 
@@ -13,7 +13,10 @@ Release notes for `quimb`.
 - Update generic TN optimizer docs.
 - add [`tn.gen_inds_loops`](quimb.tensor.tensor_core.TensorNetwork.gen_inds_loops) for generating all loops of indices in a TN.
 - add [`tn.gen_inds_connected`](quimb.tensor.tensor_core.TensorNetwork.gen_inds_connected) for generating all connected sets of indices in a TN.
-
+- make SVD fallback error catching more generic ({pull}`#238`)
+- fix some windows + numba CI issues.
+- [`approx_spectral_function`](quimb.linalg.approx_spectral.approx_spectral_function) add plotting and tracking
+- add dispatching to various tensor primitives to allow overriding
 
 (whats-new-1-8-1)=
 ## v1.8.1 (2024-05-06)

pyproject.toml

@@ -10,7 +10,6 @@ write_to = "quimb/_version.py"
 
 [tool.pytest.ini_options]
 testpaths = "tests"
-addopts = "--cov=quimb --cov-report term-missing --cov-report xml:coverage.xml --verbose --durations=10"
 filterwarnings = "once"
 
 [tool.coverage.run]

quimb/tensor/array_ops.py

@@ -165,6 +165,25 @@ def ndim(array):
         return len(array.shape)
 
 
+@compose
+def multiply_diagonal(x, v, axis, backend=None):
+    """Multiply v into x as if contracting in a diagonal matrix."""
+    newshape = tuple((-1 if i == axis else 1) for i in range(ndim(x)))
+    v_broadcast = do("reshape", v, newshape, like=backend)
+    return x * v_broadcast
+
+
+@compose
+def align_axes(*arrays, axes, backend=None):
+    """Prepare a set of arrays that should be contractible along ``axes``.
+
+    For example, block symmetric arrays need to have aligned sectors prior to
+    fusing.
+    """
+    # default implementation is nothing
+    return arrays
+
+
 # ------------- miscelleneous other backend agnostic functions -------------- #
 
 
@@ -281,7 +300,11 @@ def find_diag_axes(x, atol=1e-12):
         if shape[i] != shape[j]:
             continue
         if do(
-            "allclose", x[indxrs[i] != indxrs[j]], zero, atol=atol, like=backend
+            "allclose",
+            x[indxrs[i] != indxrs[j]],
+            zero,
+            atol=atol,
+            like=backend,
         ):
             return (i, j)
     return None