Merge pull request #734 from helmholtz-analytics/bug/731-local_op-out

fix local_op + out distributed

CHANGELOG.md

@@ -35,6 +35,7 @@
 ## Bug fixes
 - [#709](https://github.com/helmholtz-analytics/heat/pull/709) Set the encoding for README.md in setup.py explicitly.
 - [#716](https://github.com/helmholtz-analytics/heat/pull/716) Bugfix: Finding clusters by spectral gap fails when multiple diffs identical
+- [#734](https://github.com/helmholtz-analytics/heat/pull/734) Fix division by zero error in `__local_op` with out != None on empty local arrays.
 - [#735](https://github.com/helmholtz-analytics/heat/pull/735) Set return type to bool in relational functions.
 
 # v0.5.2

heat/core/_operations.py

@@ -324,7 +324,7 @@ def __local_op(operation, x, out, no_cast=False, **kwargs):
     # PyTorch always recreates the input shape and ignores broadcasting for too large buffers
     broadcast_shape = stride_tricks.broadcast_shape(x.lshape, out.lshape)
     padded_shape = (1,) * (len(broadcast_shape) - len(x.lshape)) + x.lshape
-    multiples = [int(a / b) for a, b in zip(broadcast_shape, padded_shape)]
+    multiples = [(int(a / b) if b > 0 else 0) for a, b in zip(broadcast_shape, padded_shape)]
     needs_repetition = builtins.any(multiple > 1 for multiple in multiples)
 
     # do an inplace operation into a provided buffer