# C/igraph 0.9.5

**URL:** <https://igraph.discourse.group/t/c-igraph-0-9-5/961>\
**Category:** Announcements\
**Tags:** C\
**Created:** [11 November 2021 14:32 UTC](https://igraph.discourse.group/t/c-igraph-0-9-5/961 "2021-11-11T14:32:44Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![tamas](https://yyz2.discourse-cdn.com/free1/user_avatar/igraph.discourse.group/tamas/32/1261_2.png) [@tamas](https://igraph.discourse.group/u/tamas)\
**Post date:** [11 November 2021 14:32 UTC](https://igraph.discourse.group/t/c-igraph-0-9-5/961/1 "2021-11-11T14:32:44Z")

</div>

[C/igraph](https://igraph.org/c/) 0.9.5, the fifth bugfix release of the 0.9 series, has arrived.

The source can be obtained from [the GitHub releases page](https://github.com/igraph/igraph/releases/tag/0.9.5).

This release includes bug fixes and performance improvements only.

### Fixed

- `igraph_reindex_membership()` does not allow negative membership indices any more.

- `igraph_rewire_directed_edges()` now generates multigraphs when edge directions are ignored, to make it consistent with the directed case.

- Fixed a bug in `igraph_gomory_hu_tree()` that returned only the equivalent flow tree instead of the cut tree.

- Fixed a bug in the `IGRAPH_TO_UNDIRECTED_COLLAPSE` mode of `igraph_to_undirected()` that provided an incorrect merge vector to the attribute handler, leading to problems when edge attributes were merged using an attribute combination.

- Fixed the behaviour of the `IGRAPH_ENABLE_LTO` option when it was set to `AUTO`; earlier versions had a bug where `AUTO` simply checked whether LTO is supported but then did not use LTO even if it was supported.

- When using igraph from a CMake project, it is now checked that the project has the C++ language enabled. This is necessary for linking to igraph with CMake.

### Other

- Improved the root selection method for disconnected graphs in the Reingold-Tilford layout (#1836). The new root selection method provides nicer results if the graph is not a tree, although it is still recommended to use the Sugiyama layout instead, unless the input graph is _almost_ a tree, in which case Reingold-Tilfold may still be preferred.

- `igraph_decompose()` is now much faster for large graphs containing many isolates or small components.

- `igraph_largest_cliques()` and `igraph_clique_number()` were re-written to use `igraph_maximal_cliques_callback()` so they are much faster now.

- The vendored GLPK has been upgraded to GLPK 5.0.

- Documentation improvements.