docs: Fix SegFault in notebook 7

Author: JDBetteridge

examples/userapi/07_functions_on_subdomains.ipynb

@@ -1070,15 +1070,15 @@
    "outputs": [],
    "source": [
     "nsnaps = 30\n",
-    "factor = round(nt/nsnaps)\n",
+    "factor = int(np.ceil(nt/nsnaps))\n",
     "\n",
     "time_subsampled = ConditionalDimension('t_sub', parent=model.grid.time_dim, factor=factor)\n",
     "\n",
-    "u_save = TimeFunction(name='usave', grid=snapshotdomain, time_order=2, space_order=2,\n",
+    "u_save = TimeFunction(name='usave', grid=snapshotdomain, time_order=0, space_order=2,\n",
     "                      save=nsnaps, time_dim=time_subsampled)\n",
     "\n",
     "# \"Normal\" snapshotting for comparison\n",
-    "u_save_grid = TimeFunction(name='usavegrid', grid=model.grid, time_order=2, space_order=2,\n",
+    "u_save_grid = TimeFunction(name='usavegrid', grid=model.grid, time_order=0, space_order=2,\n",
     "                           save=nsnaps, time_dim=time_subsampled)"
    ]
   },
@@ -2499,7 +2499,8 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "assert np.isclose(np.linalg.norm(u_save.data), 53.853184, atol=0, rtol=1e-4)"
+    "assert np.isclose(np.linalg.norm(u_save.data), 54.026115, atol=0, rtol=1e-4)\n",
+    "assert np.isclose(np.linalg.norm(u_save_grid.data), 77.89853, atol=0, rtol=1e-4)"
    ]
   },
   {