[with patch; positive review] NTL abort in Integers(125)[]

[jbmohler]

This NTL abort should be handled with a python exception:

sage: R.<x> = Integers(125)[]
sage: (3*x).quo_rem(5*x)
InvMod: inverse undefined
/home/joel/sage/local/bin/sage-sage: line 214: 31177 Aborted                 sage-ipython "$@" -c "$SAGE_STARTUP_COMMAND;"

[mabshoff]

Looks like somebody is not checking the return value of some NTL function:

----------------------------------------------------------------------
| SAGE Version 2.10.4, Release Date: 2008-03-16                      |
| Type notebook() for the GUI, and license() for information.        |
----------------------------------------------------------------------
sage: R.<x> = Integers(125)[]
sage: (3*x).quo_rem(5*x)
InvMod: inverse undefined

Program received signal SIGABRT, Aborted.
[Switching to Thread 46994942697312 (LWP 9397)]
0x00002abddcbcc07b in raise () from /lib/libc.so.6
(gdb) bt
#0  0x00002abddcbcc07b in raise () from /lib/libc.so.6
#1  0x00002abddcbcd84e in abort () from /lib/libc.so.6
#2  0x00002abddddab097 in NTL::Error (s=<value optimized out>) at tools.c:14
#3  0x00002abdddcfeee9 in NTL::InvMod (a=<value optimized out>, n=125) at ZZ.c:351
#4  0x00002abdddd716c6 in NTL::PlainDivRem (q=@0x2abdf2106950, r=@0x2abdf21069c0, a=@0x2abdefb18720, b=@0xffffffffffffffff)
    at ../include/NTL/lzz_p.h:278
#5  0x00002abde75b842e in __pyx_pf_4sage_5rings_10polynomial_25polynomial_modn_dense_ntl_28Polynomial_dense_modn_ntl_zz_quo_rem (__pyx_v_self=0x2abdefb186e0, __pyx_v_right=0x2abdf21068a0) at sage/rings/polynomial/polynomial_modn_dense_ntl.cpp:7456
#6  0x0000000000484a96 in PyEval_EvalFrameEx (f=0x14d00c0, throwflag=<value optimized out>) at Python/ceval.c:3552
#7  0x00000000004856ab in PyEval_EvalCodeEx (co=0x2abdf05a1468, globals=<value optimized out>,
    locals=<value optimized out>, args=0x0, argcount=0, kws=0x0, kwcount=0, defs=0x0, defcount=0, closure=0x0)
    at Python/ceval.c:2831
#8  0x0000000000484435 in PyEval_EvalFrameEx (f=0x149ea60, throwflag=<value optimized out>) at Python/ceval.c:494
#9  0x00000000004856ab in PyEval_EvalCodeEx (co=0x2abde013e918, globals=<value optimized out>,
    locals=<value optimized out>, args=0x1b43f00, argcount=2, kws=0x1b43f10, kwcount=0, defs=0x0, defcount=0, closure=0x0)
    at Python/ceval.c:2831
#10 0x0000000000483dcd in PyEval_EvalFrameEx (f=0x1b43d60, throwflag=<value optimized out>) at Python/ceval.c:3660
#11 0x00000000004856ab in PyEval_EvalCodeEx (co=0x2abde013e828, globals=<value optimized out>,
    locals=<value optimized out>, args=0x1, argcount=3, kws=0x1b47730, kwcount=0, defs=0x2abde01ab5c0, defcount=2,
    closure=0x0) at Python/ceval.c:2831

[wjp]

Calls to NTL's div (and div-like) functions were only wrapped in _sig_on/_sig_off if the polynomials were large enough in some cases. The patch I'm attaching removes the condition in these cases, and adds a doctest for one of them.

[wjp]

The patch in ntl_div_sig_after2903.patch adapts the doctest to the patch for #2903. (Only apply it if #2903 is also applied.)

[mabshoff]

Both patches look good to me. Positive review.

Cheers,

Michael

[mabshoff]

Merged in Sage 3.0.alpha6