From 95ba9d1d5da512791abe788377de5ad840c48f9d Mon Sep 17 00:00:00 2001
From: Andrew Rowley <Andrew.Rowley@manchester.ac.uk>
Date: Tue, 31 Oct 2023 09:44:11 +0000
Subject: [PATCH] Fix and test

---
 pacman/model/graphs/common/mdslice.py | 12 ++++++------
 unittests/model_tests/test_mdslice.py |  7 +++++++
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/pacman/model/graphs/common/mdslice.py b/pacman/model/graphs/common/mdslice.py
index c157f501b..75cf3cbef 100644
--- a/pacman/model/graphs/common/mdslice.py
+++ b/pacman/model/graphs/common/mdslice.py
@@ -159,23 +159,23 @@ def from_string(cls, as_str):
     def get_relative_indices(self, app_vertex_indices):
         n_dims = len(self._atoms_shape)
         remainders = app_vertex_indices
-        last_per_core = 0
+        cum_last_core = 1
         rel_index = numpy.zeros(len(app_vertex_indices))
-        for n in n_dims:
+        for n in range(n_dims):
             # Work out the index in this dimension
             global_index_d = remainders % self._atoms_shape[n]
 
             # Work out the index in this dimension relative to the core start
-            rel_index_d = global_index_d - self._starts[n]
+            rel_index_d = global_index_d - self._start[n]
 
             # Update the total relative index using the position in this
             # dimension
-            rel_index = (rel_index * last_per_core) + rel_index_d
+            rel_index += rel_index_d * cum_last_core
 
             # Prepare for next round of the loop by removing what we used
             # of the global index and remembering the sizes in this
             # dimension
             remainders = remainders // self._atoms_shape[n]
-            last_per_core = self._shape[n]
+            cum_last_core *= self._shape[n]
 
-        return rel_index
+        return rel_index.astype(numpy.uint32)
diff --git a/unittests/model_tests/test_mdslice.py b/unittests/model_tests/test_mdslice.py
index 3352f59cb..d00a10218 100644
--- a/unittests/model_tests/test_mdslice.py
+++ b/unittests/model_tests/test_mdslice.py
@@ -76,3 +76,10 @@ def test_3b(self):
                              list(s.get_raster_ids()))
         s2 = MDSlice.from_string(str(s))
         self.assertEqual(s, s2)
+
+    def test_get_relative_indices(self):
+        s = MDSlice(22, 89, (2, 3, 2), (4, 3, 0), (6, 9, 4))
+        # Going over the raster IDs should result in a line over the core
+        self.assertListEqual(list(range(2 * 3 * 2)),
+                             list((s.get_relative_indices(
+                                 s.get_raster_ids()))))