Address PR review comments: remove unused bool_compat, stale docs, and use torch.sparse.mm

Author: saitcakmak

linear_operator/operators/_linear_operator.py

@@ -80,7 +80,7 @@ def _implements_second_arg(torch_function: Callable) -> Callable:
     where the first argument of the function is a torch.Tensor and the
     second argument is a LinearOperator
 
-    Examples of this include :meth:`torch.cholesky_solve`, `torch.linalg.solve`, or `torch.matmul`.
+    Examples of this include `torch.linalg.solve` or `torch.matmul`.
     """
 
     @functools.wraps(torch_function)

linear_operator/utils/deprecation.py

@@ -4,10 +4,6 @@
 import functools
 import warnings
 
-import torch
-
-bool_compat = torch.bool
-
 
 class DeprecationError(Exception):
     pass

linear_operator/utils/sparse.py

@@ -125,7 +125,7 @@ def bdsmm(sparse, dense):
         return res
 
     else:
-        return torch.mm(sparse, dense)
+        return torch.sparse.mm(sparse, dense)
 
 
 def sparse_eye(size):