[GiNaC-list] matrix::solve()-related problems

[Vitaly Magerya]

On 01/26/2018 02:24 PM, I wrote:
>     matrix size  gauss time  bareiss time  gauss/bareiss
>     2x2          0.00416815  0.00361022    1.15454
>     3x3          0.0195643   0.0141638     1.38129
>     4x4          0.0896266   0.0666258     1.34522
>     5x5          0.205633    0.185446      1.10885
>     6x6          0.730309    0.979617      0.745505
>     7x7          1.29834     3.14298       0.413093
>     8x8          2.46307     9.70648       0.253755
>     9x9          4.4289      (segfaults)
>     10x10        8.39434     (segfaults)

These segfaults have this sort of backtrace:

#1  0x00007ffff7a07f79 in GiNaC::ex::construct_from_basic(...)
#2  0x00007ffff79e19e2 in GiNaC::basic::subs_one_level(...) const
#3  0x00007ffff7b3d235 in GiNaC::power::subs(...) const
#4  0x00007ffff7a0ba11 in GiNaC::expairseq::subschildren(...) const
#5  0x00007ffff7a0bd64 in GiNaC::expairseq::subs(...) const
#6  0x00007ffff7a08d4e in GiNaC::ex::subs(...) const
#7  0x00007ffff7aeb6c0 in GiNaC::gcd(...)
#8  0x00007ffff7aea806 in GiNaC::gcd_pf_pow(...)
#9  0x00007ffff7aebbd0 in GiNaC::gcd(...)
#10 0x00007ffff7aeac26 in GiNaC::gcd_pf_pow(...)
#11 0x00007ffff7aebbd0 in GiNaC::gcd(...)

(repeat the last two lines a whole bunch of times)

#20147 0x00007ffff7aebbd0 in GiNaC::gcd(...)
#20148 0x00007ffff7aeac26 in GiNaC::gcd_pf_pow(...)
#20149 0x00007ffff7aea2f8 in GiNaC::gcd_pf_pow(...)
#20150 0x00007ffff7aebbd0 in GiNaC::gcd(...)
#20151 0x00007ffff7af214a in GiNaC::frac_cancel(...)
#20152 0x00007ffff7af2b13 in GiNaC::mul::normal(...) const
#20153 0x00007ffff7af2dd0 in GiNaC::add::normal(...) const
#20154 0x00007ffff7af2947 in GiNaC::mul::normal(...) const
#20155 0x00007ffff7ae613c in GiNaC::ex::normal() const
#20156 0x00007ffff7ac73cc in GiNaC::matrix::solve(...) const
#20157 0x0000000000404671 in main () at gauss-vs-bareiss.cpp:35

I think this is the same problem Patrick Schulz reported a bit earlier
over here:

https://www.ginac.de/pipermail/ginac-list/2018-January/002168.html