fflas-ffpack master: Error tuning fflas-ffpack, FFPACK::CharpolyFailed on linuxmint-21.1-minimal

[mkoeppe]

On linuxmint-21.1-minimal, tested using

• ci-sage: Update #386

=================================================
    [fflas_ffpack-git]   ========= FFLAS-FFPACK CharPoly Autotuning =========
    [fflas_ffpack-git]   =================================================
    [fflas_ffpack-git]   
    [fflas_ffpack-git]   
    [fflas_ffpack-git]   ---------------------------------------------------------------------
    [fflas_ffpack-git]   Tue Jan  2 06:32:55 2024
    [fflas_ffpack-git]   
    [fflas_ffpack-git]   Threshold for ArithProg CharPoly algorithm (using ModularBalanced<double> modulo 2097169)
    [fflas_ffpack-git]   
    [fflas_ffpack-git]   Charpoly:  n = 800  degree    seconds            Gfops
    [fflas_ffpack-git]                                16         0.128364          10.7694  
    [fflas_ffpack-git]                                18         0.126115          10.9614  
    [fflas_ffpack-git]                                20         0.122542           11.281  
    [fflas_ffpack-git]                                22         0.124405          11.1121  
    [fflas_ffpack-git]                                24         0.124247          11.1262  
    [fflas_ffpack-git]                                26         0.126216          10.9527  
    [fflas_ffpack-git]                                28         0.1[233](https://github.com/linbox-team/fflas-ffpack/actions/runs/7382353719/job/20082051368?pr=386#step:14:234)05          11.2112  
    [fflas_ffpack-git]                                30          0.12327          11.2144  
    [fflas_ffpack-git]                                32         0.120128          11.5078  
    [fflas_ffpack-git]                                34         0.116568          11.8592  
    [fflas_ffpack-git]                                36         0.128554          10.7535  
    [fflas_ffpack-git]                                38         0.125419          11.0223  
    [fflas_ffpack-git]                                40         0.119676          11.5512  
    [fflas_ffpack-git]                                42         0.120824          11.4414  
    [fflas_ffpack-git]                                44         0.125166          11.0445  
    [fflas_ffpack-git]                                46         0.121926           11.338  
    [fflas_ffpack-git]                                48         0.118205          11.6949  
    [fflas_ffpack-git]                                50          0.11446          12.0776  
    [fflas_ffpack-git]                                52          0.11609           11.908  
    [fflas_ffpack-git]                                54         0.129748          10.6545  
    [fflas_ffpack-git]                                56         0.132074          10.4668  
    [fflas_ffpack-git]                                58         0.127898          10.8086  
    [fflas_ffpack-git]                                60         0.130426          10.5991  
    [fflas_ffpack-git]                                62         0.122847           11.253  
    [fflas_ffpack-git]   
    [fflas_ffpack-git]   defined __FFLASFFPACK_ARITHPROG_THRESHOLD to 50
    [fflas_ffpack-git]   
    [fflas_ffpack-git]   ---------------------------------------------------------------------
    [fflas_ffpack-git]   Tue Jan  2 06:33:07 2024
    [fflas_ffpack-git]   
    [fflas_ffpack-git]   Threshold between CharPoly algorithms LUKrylov <-> ArithProg (using ModularBalanced<double> modulo 4194301)
    [fflas_ffpack-git]   
    [fflas_ffpack-git]   Charpoly:  n                   LUKrylov                        ArithProg
    [fflas_ffpack-git]                       seconds            Gfops          seconds            Gfops
    [fflas_ffpack-git]         1024         0.233906          12.3943         0.399735          7.25256
    [fflas_ffpack-git]         1152         0.[236](https://github.com/linbox-team/fflas-ffpack/actions/runs/7382353719/job/20082051368?pr=386#step:14:237)326          17.4666         0.421991          9.78179
    [fflas_ffpack-git]         1280         0.323072          17.5265         0.562646          10.0637
    [fflas_ffpack-git]         1408         0.409733          18.3938          0.67757          11.1229
    [fflas_ffpack-git]         1536         0.564611          17.3296         0.987837          9.90495
    [fflas_ffpack-git]         1664         0.665488          18.6932          1.01767          12.2[241](https://github.com/linbox-team/fflas-ffpack/actions/runs/7382353719/job/20082051368?pr=386#step:14:242)
    [fflas_ffpack-git]         1792         0.862928          18.0054          1.25851          12.3458
    [fflas_ffpack-git]         1920          1.08975          17.5364          1.44225          13.[250](https://github.com/linbox-team/fflas-ffpack/actions/runs/7382353719/job/20082051368?pr=386#step:14:251)4
    [fflas_ffpack-git]         2048          1.48028          15.6678          2.14421          10.8165
    [fflas_ffpack-git]         2176          1.76947          15.7216          1.99125          13.9706
    [fflas_ffpack-git]         2304           2.[256](https://github.com/linbox-team/fflas-ffpack/actions/runs/7382353719/job/20082051368?pr=386#step:14:257)3          14.6357          2.38358          13.8542
    [fflas_ffpack-git]   terminate called after throwing an instance of 'FFPACK::CharpolyFailed'
    [fflas_ffpack-git]   make[4]: *** [Makefile:976: autotune] Error 134
    [fflas_ffpack-git]   make[3]: *** [Makefile:1012: autotune] Error 2
    [fflas_ffpack-git]   Error tuning fflas-ffpack

https://github.com/linbox-team/fflas-ffpack/actions/runs/7382353719/job/20082051368?pr=386#step:14:233