Handle dtypes during direcsum

Author: Danfoa

escnn/group/representation.py

@@ -562,11 +562,16 @@ def directsum(reprs: List[escnn.group.Representation],
         irreps += r.irreps
 
     size = sum([r.size for r in reprs])
-    
-    cob = np.zeros((size, size))
-    cob_inv = np.zeros((size, size))
+
+    # Determine the dtype for the change of basis diagonal matrix to avoid unsafe casting.
+    dtype = np.complex if np.any([np.iscomplexobj(rep.change_of_basis) for rep in reprs]) else np.float
+
+    cob = np.zeros((size, size), dtype=dtype)
+    cob_inv = np.zeros((size, size), dtype=dtype)
     p = 0
     for r in reprs:
+        assert np.can_cast(r.change_of_basis.dtype, cob.dtype), \
+            f"Cannot safely cast {r.change_of_basis.dtype} to {cob.dtype}"
         cob[p:p + r.size, p:p + r.size] = r.change_of_basis
         cob_inv[p:p + r.size, p:p + r.size] = r.change_of_basis_inv
         p += r.size
@@ -580,7 +585,9 @@ def directsum(reprs: List[escnn.group.Representation],
 
     supported_nonlinearities = set.intersection(*[r.supported_nonlinearities for r in reprs])
 
-    return Representation(group, name, irreps, change_of_basis, supported_nonlinearities, change_of_basis_inv=change_of_basis_inv)
+    return Representation(
+        group, name, irreps, change_of_basis, supported_nonlinearities, change_of_basis_inv=change_of_basis_inv
+    )
 
 
 def disentangle(repr: Representation) -> Tuple[np.ndarray, List[Representation]]: