SegFault for BlockElimination

[mengyuest]

I encountered Segmentation Fault when using BlockElimination function. The minimum test code is as followed:

using Polyhedra, CDDLib
A=[-0.5458700320410754 -0.43028245741634163 -0.32949085078374596 -2.0178905562651726 1.0 0.0 0.0; -0.001696359345425646 -0.5944052771561518 -0.14259145370038157 -0.5715464802979783 0.0 1.0 0.0; 0.11176371186473642 0.16920950931092318 -0.6603345932930139 -0.11228115664803578 0.0 0.0 1.0; 0.5458700320410754 0.43028245741634163 0.32949085078374596 2.0178905562651726 -1.0 0.0 0.0; 0.001696359345425646 0.5944052771561518 0.14259145370038157 0.5715464802979783 0.0 -1.0 0.0; -0.11176371186473642 -0.16920950931092318 0.6603345932930139 0.11228115664803578 0.0 0.0 -1.0; -1.0 0.10091143255328394 3.4102811211934987 -6.813065334385856 0.0 0.0 0.0; 1.0 -0.8932312066317769 0.7730763460460294 2.524023981062126 0.0 0.0 0.0; 1.0 -0.0930882189983393 1.7475328342666678 4.495570410302662 0.0 0.0 0.0; -1.0 -0.05182954771533831 -1.1189515717142475 -3.9532525226843815 0.0 0.0 0.0; 1.0 4.239841226638941 -8.774257911319019 -2.2499336877985545 0.0 0.0 0.0; -1.0 1.0414219678515158 1.033883503426593 -0.9840648095304564 0.0 0.0 0.0; 1.0 -0.001284573155440541 -1.6845061382720732 -1.0153065939984884 0.0 0.0 0.0; 1.0 -4.299428761845123 -3.940453969462597 6.702373679526568 0.0 0.0 0.0; -1.0 0.0 0.0 0.0 0.0 0.0 0.0; 0.0 1.0 0.0 0.0 0.0 0.0 0.0]
b=[0.3653256599471767, 0.4574210313524346, 0.35534066564751254, -0.3653256599471767, -0.4574210313524346, -0.35534066564751254, -2.9769531018983972, 0.8613646098710365, 3.3649667529429204, -2.093853811646953, 8.893608931702863, 0.7565246179371888, 1.433621499051063, -3.9487728883626625, -1.0, 2.0]
poly_in = polyhedron(hrep(A,b), CDDLib.Library(:float))
poly_out = eliminate(poly_in, collect(1:4), BlockElimination())

I am using Julia v1.4.2 and Ubuntu 18.04. Further package details are as followed:

  [6e4b80f9] BenchmarkTools v0.5.0
  [3391f64e] CDDLib v0.6.3
  [5789e2e9] FileIO v1.4.5
  [587475ba] Flux v0.11.1
  [60bf3e95] GLPK v0.13.0
  [033835bb] JLD2 v0.3.1
  [682c06a0] JSON v0.21.1
  [4076af6c] JuMP v0.21.5
  [b4f0291d] LazySets v1.37.14
  [23992714] MAT v0.9.2
  [15e1cf62] NPZ v0.4.0
  [91a5bcdd] Plots v1.6.12
  [67491407] Polyhedra v0.6.11
  [d330b81b] PyPlot v2.9.0
  [9f7883ad] Tracker v0.2.13
  [37e2e46d] LinearAlgebra

Any suggestion on this? Thanks.

[mforets]

fwiw, i can repro on Julia v1.6.0 and Polyhedra v0.6.13.

[blegat]

Thanks for the small reproducible example! Turns out this is a bug in cddlib: cddlib/cddlib#61.
Once this is fixed, this should throw Numerically inconsistent. It still won't make it work but it's considerably better than a segfault ^^

[nsajko]

ftr this still isn't fixed after the cddlib pull request is merged

[blegat]

Do you get a segfault or another error ?

[schillic]

Do you get a segfault or another error ?

Julia v1.8 is still affected by the segfault.

  [3391f64e] CDDLib v0.9.1
  [67491407] Polyhedra v0.7.5

---

I am not very familiar with how the jll library is built, but maybe it has to be updated to include the fix. The latest release over at cddlib is from December 2020 (i.e., does not contain the fix), and the version used at juliapackages indicates this even older commit from February 2020 (i.e., does not contain the fix either).

[odow]

This is still a problem. Yggdrasil build is missing these commits:

cddlib/cddlib@87220b4...master

I guess the hesitation is because there hasn't been an official release yet.

[odow]

See JuliaPackaging/Yggdrasil#8142

[schillic]

Thanks for the small reproducible example! Turns out this is a bug in cddlib: cddlib/cddlib#61. Once this is fixed, this should throw Numerically inconsistent.

Well, not quite:

ERROR: ddf_BlockElimination returned a NULL pointer but did not provide any error.
Please report this by opening an issue at https://github.com/JuliaPolyhedra/CDDLib.jl.