[postgis-tickets] [PostGIS] #4188: Division by zero in kmeans

[PostGIS]

#4188: Division by zero in kmeans
------------------------+---------------------------
 Reporter:  Algunenano  |      Owner:  Algunenano
     Type:  defect      |     Status:  assigned
 Priority:  medium      |  Milestone:  PostGIS 2.5.1
Component:  postgis     |    Version:  2.5.x
 Keywords:              |
------------------------+---------------------------
 I'm getting a warning when running regress tests under clang's sanitizer
 (`-fsanitize=undefined -fsanitize-trap=undefined`):
 {{{
                 Stack trace of thread 26485:
                 #0  0x00007f611e683c75 update_means (postgis-3.0.so)
                 #1  0x00007f611e682c02 kmeans (postgis-3.0.so)
                 #2  0x00007f611e6812c2 lwgeom_cluster_2d_kmeans
 (postgis-3.0.so)
                 #3  0x00007f611e3e2837 ST_ClusterKMeans (postgis-3.0.so)
                 #4  0x000055c82ba2e281 ExecWindowAgg (postgres)
                 #5  0x000055c82ba100d6 fetch_input_tuple (postgres)
                 #6  0x000055c82ba0eb37 ExecAgg (postgres)
                 #7  0x000055c82b9fc70c standard_ExecutorRun (postgres)
                 #8  0x000055c82bb7d8e3 PortalRunSelect (postgres)
                 #9  0x000055c82bb7d444 PortalRun (postgres)
                 #10 0x000055c82bb7c27c exec_simple_query (postgres
 }}}

 PR in https://github.com/postgis/postgis/pull/309

 At least 2.5 and trunk are affected.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/4188>
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