factorize crashes

[steenpass]

> ring r = (0,s), (a,b), dp;
> minpoly = s6+21s4+27s2-49;
> poly p = -a6b2+a2b6+4*a6+9*a4b2-9*a2b4-4*b6-36*a4+36*b4+81*a2-81*b2;
> factorize(p);
zz_pX InvMod: can't compute multiplicative inverse
Singular : signal 6 (v: 3160):
current line:>>factorize(p);<<
Segment fault/Bus error occurred at 7fff433a4cb0 because of 206 (r:1372776459)
please inform the authors
trying to restart...
> 

[Oleksandr]

Hmm, this also holds for SW. The GDB back-trace is as follows:

(gdb) bt
#0  0x00007ffff5b9f1c9 in raise () from /usr/lib/libc.so.6
#1  0x00007ffff5ba05c8 in abort () from /usr/lib/libc.so.6
#2  0x00007ffff77095fe in _ntl_abort () from /usr/lib/libntl.so.0
#3  0x00007ffff77a0d10 in NTL::InvMod(NTL::zz_pX&, NTL::zz_pX const&, NTL::zz_pX const&) () from /usr/lib/libntl.so.0
#4  0x00007ffff778ed19 in NTL::PlainRem(NTL::zz_pEX&, NTL::zz_pEX const&, NTL::zz_pEX const&, NTL::vec_zz_pX&) ()
   from /usr/lib/libntl.so.0
#5  0x00007ffff7791847 in NTL::GCD(NTL::zz_pEX&, NTL::zz_pEX const&, NTL::zz_pEX const&) () from /usr/lib/libntl.so.0
#6  0x00007ffff7798226 in ?? () from /usr/lib/libntl.so.0
#7  0x00007ffff779a2e2 in NTL::FindRoots(NTL::vec_zz_pE&, NTL::zz_pEX const&) () from /usr/lib/libntl.so.0
#8  0x00007ffff779ad40 in NTL::RootEDF(NTL::vec_zz_pEX&, NTL::zz_pEX const&, long) () from /usr/lib/libntl.so.0
#9  0x00007ffff779d66b in NTL::SFCanZass(NTL::vec_zz_pEX&, NTL::zz_pEX const&, long) () from /usr/lib/libntl.so.0
#10 0x00007ffff779da2a in NTL::CanZass(NTL::vec_pair_zz_pEX_long&, NTL::zz_pEX const&, long) () from /usr/lib/libntl.so.0
#11 0x00007ffff7aa614a in factorize (f=..., alpha=...) at ../../factory/cf_factor.cc:762
#12 0x00007ffff7af078c in biFactorize (F=..., v=...) at ../../factory/facBivar.cc:371
#13 0x00007ffff7aad3c4 in ratBiSqrfFactorize (G=..., v=...) at ../../factory/facBivar.h:97
#14 0x00007ffff7aada4a in ratBiFactorize (G=..., v=..., substCheck=substCheck@entry=false) at ../../factory/facBivar.h:238
#15 0x00007ffff7aade6e in ratBiFactorize (G=..., v=..., substCheck=substCheck@entry=true) at ../../factory/facBivar.h:152
#16 0x00007ffff7aa7b1a in ratFactorize (G=..., v=..., substCheck=substCheck@entry=true) at ../../factory/facFactorize.h:71
#17 0x00007ffff7aa5f6b in factorize (f=..., alpha=...) at ../../factory/cf_factor.cc:838
#18 0x0000000000603151 in singclap_factorize (f=0x7ffff596e260, v=0x7fffffffa268, with_exps=0, r=0x7ffff5974030)
    at ../../../libpolys/polys/clapsing.cc:814
#19 0x000000000041c68e in jjFAC_P(sleftv*, sleftv*) ()
#20 0x000000000042fb89 in iiExprArith1(sleftv*, sleftv*, int) ()
#21 0x00000000004106ad in yyparse() ()
#22 0x000000000040a1dc in main ()

Seems to be due to NTL Zass...

[hannes]

minpoly is not irreducible:

> ring r = 0,s, dp;
> factorize ( s6+21s4+27s2-49);
[1]:
   _[1]=1
   _[2]=s-1
   _[3]=s+1
   _[4]=s4+22s2+49
[2]:
   1,1,1,1