#10250: segfault when multiplying QQ constant and SR vector (with user basis)
------------------------------+---------------------------------------------
Reporter: jason | Owner: jason, was
Type: defect | Status: new
Priority: major | Milestone:
Component: linear algebra | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
------------------------------+---------------------------------------------
This code worked in Sage 4.5.2. I just realized that it now gives a
segfault in 4.6. Does anyone know what is going on?
{{{
sage: A=matrix(QQ, [[2,1],[0,3]])
sage: eval, evecs,mult=A.eigenvectors_right()[0]
sage: evec=evecs[0]
sage: unitevec=evec/evec.norm()
sage: unitevec
(1/2*sqrt(2), 1/2*sqrt(2))
sage: parent(eval)
Rational Field
sage: eval
3
}}}
and then:
{{{
sage: w=(SR2)(unitevec)
sage: parent(w) # works fine
Vector space of dimension 2 over Symbolic Ring
sage: eval*w
(3/2*sqrt(2), 3/2*sqrt(2))
}}}
but here's the problem:
{{{
sage: parent(unitevec) # gives problem
Vector space of degree 2 and dimension 1 over Symbolic Ring
User basis matrix:
[1 1]
sage: eval*unitevec
------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred in Sage.
This probably occurred because a *compiled* component
of Sage has a bug in it (typically accessing invalid memory)
or is not properly wrapped with _sig_on, _sig_off.
You might want to run Sage under gdb with 'sage -gdb' to debug this.
Sage will now terminate (sorry).
------------------------------------------------------------
}}}
Here is a backtrace using sage -gdb, which indicates a problem in ginac or
pynac.
{{{
sage: eval*unitevec
Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: 13 at address: 0x0000000000000000
0x00007fff8294a7a2 in __dynamic_cast ()
(gdb) bt
#0 0x00007fff8294a7a2 in __dynamic_cast ()
#1 0x000000010798ffcc in is_a<GiNaC::relational> [inlined] () at
/Users/grout/sage-trees/sage-4.6/local/include/pynac/basic.h:939
#2 0x000000010798ffcc in is_a<GiNaC::relational> [inlined] () at
/Users/grout/sage-trees/sage-4.6/local/include/pynac/ex.h:939
#3 0x000000010798ffcc in
__pyx_f_4sage_8symbolic_10expression_10Expression__mul_
(__pyx_v_left=0x10c825a70, __pyx_v_right=0x10c8281d0,
__pyx_skip_dispatch=<value temporarily unavailable, due to optimizations>)
at ex.h:11284
#4 0x0000000104be0632 in
__pyx_f_4sage_7modules_19free_module_element_31FreeModuleElement_generic_dense__rmul_
(__pyx_v_self=0x10c81e628, __pyx_v_left=0x10c825a70,
__pyx_skip_dispatch=<value temporarily unavailable, due to optimizations>)
at sage/modules/free_module_element.c:15600
#5 0x00000001022b5b7f in
__pyx_f_4sage_9structure_14coerce_actions_16LeftModuleAction__call_
(__pyx_v_self=0x1006be758, __pyx_v_g=0x10c825a70, __pyx_v_a=0x10c81e628,
__pyx_skip_dispatch=<value temporarily unavailable, due to optimizations>)
at sage/structure/coerce_actions.c:5437
#6 0x000000010223fe62 in __pyx_pf_4sage_10categories_6action_6Action_act
(__pyx_v_self=0x1006be758, __pyx_args=0x10bd2e638, __pyx_kwds=0x0) at
sage/categories/action.c:2563
#7 0x000000010000bcd2 in PyObject_Call ()
#8 0x00000001022b68eb in
__pyx_pf_4sage_9structure_14coerce_actions_12ModuleAction___init__
(__pyx_v_self=0x1006be758, __pyx_args=<value temporarily unavailable, due
to optimizations>, __pyx_kwds=<value temporarily unavailable, due to
optimizations>) at sage/structure/coerce_actions.c:5133
#9 0x000000010006d8c5 in type_call ()
#10 0x000000010000bcd2 in PyObject_Call ()
#11 0x00000001022b8673 in
__pyx_pf_4sage_9structure_14coerce_actions_detect_element_action
(__pyx_self=<value temporarily unavailable, due to optimizations>,
__pyx_args=<value temporarily unavailable, due to optimizations>,
__pyx_kwds=<value temporarily unavailable, due to optimizations>) at
sage/structure/coerce_actions.c:4184
#12 0x000000010000bcd2 in PyObject_Call ()
#13 0x0000000101f9988c in
__pyx_f_4sage_9structure_6parent_6Parent_discover_action
(__pyx_v_self=0x10bed9b40, __pyx_v_S=0x1021654d0, __pyx_v_op=0x1006418c0,
__pyx_v_self_on_left=0) at sage/structure/parent.c:14710
#14 0x0000000101f5b825 in
__pyx_f_4sage_9structure_10parent_old_6Parent_get_action_c_impl
(__pyx_v_self=0x10bed9b40, __pyx_v_S=0x1021654d0, __pyx_v_op=0x1006418c0,
__pyx_v_self_on_left=0) at sage/structure/parent_old.c:3254
#15 0x0000000101f5ba6f in
__pyx_pf_4sage_9structure_10parent_old_6Parent_get_action_impl
(__pyx_v_self=0x10bed9b40, __pyx_args=<value temporarily unavailable, due
to optimizations>, __pyx_kwds=<value temporarily unavailable, due to
optimizations>) at sage/structure/parent_old.c:3204
#16 0x000000010000bcd2 in PyObject_Call ()
#17 0x0000000101f5c424 in
__pyx_f_4sage_9structure_10parent_old_6Parent_get_action_c
(__pyx_v_self=0x10bed9b40, __pyx_v_S=0x1021654d0, __pyx_v_op=0x1006418c0,
__pyx_v_self_on_left=0, __pyx_skip_dispatch=<value temporarily
unavailable, due to optimizations>) at sage/structure/parent_old.c:2892
#18 0x0000000101f4f359 in
__pyx_f_4sage_9structure_10parent_old_6Parent__get_action_
(__pyx_v_self=0x10bed9b40, __pyx_v_other=0x1021654d0,
__pyx_v_op=0x1006418c0, __pyx_v_self_on_left=0, __pyx_skip_dispatch=<value
temporarily unavailable, due to optimizations>) at
sage/structure/parent_old.c:6069
#19 0x0000000101f9b9a4 in
__pyx_f_4sage_9structure_6parent_6Parent_get_action
(__pyx_v_self=0x10bed9b40, __pyx_v_S=0x1021654d0,
__pyx_skip_dispatch=<value temporarily unavailable, due to optimizations>,
__pyx_optional_args=<value temporarily unavailable, due to optimizations>)
at sage/structure/parent.c:13731
#20 0x00000001020aaa87 in
__pyx_f_4sage_9structure_6coerce_24CoercionModel_cache_maps_discover_action
(__pyx_v_self=0x101f38710, __pyx_v_R=0x1021654d0, __pyx_v_S=0x10bed9b40,
__pyx_v_op=0x1006418c0, __pyx_skip_dispatch=<value temporarily
unavailable, due to optimizations>) at sage/structure/coerce.c:11909
#21 0x00000001020afcf1 in
__pyx_f_4sage_9structure_6coerce_24CoercionModel_cache_maps_get_action
(__pyx_v_self=0x101f38710, __pyx_v_R=0x1021654d0, __pyx_v_S=0x10bed9b40,
__pyx_v_op=0x1006418c0, __pyx_skip_dispatch=<value temporarily
unavailable, due to optimizations>) at sage/structure/coerce.c:10837
#22 0x00000001020bbe36 in
__pyx_f_4sage_9structure_6coerce_24CoercionModel_cache_maps_bin_op
(__pyx_v_self=0x101f38710, __pyx_v_x=0x1006b56b0, __pyx_v_y=0x10c8292b8,
__pyx_v_op=0x1006418c0, __pyx_skip_dispatch=<value temporarily
unavailable, due to optimizations>) at sage/structure/coerce.c:6080
#23 0x000000010203165d in
__pyx_pf_4sage_9structure_7element_11RingElement___mul__
(__pyx_v_left=0x1006b56b0, __pyx_v_right=0x10c8292b8) at
sage/structure/element.c:11399
#24 0x000000010000bfbc in binary_op1 ()
#25 0x000000010000e5a8 in PyNumber_Multiply ()
#26 0x00000001000b35df in PyEval_EvalFrameEx ()
#27 0x00000001000b9010 in PyEval_EvalCodeEx ()
#28 0x00000001000b7799 in PyEval_EvalFrameEx ()
#29 0x00000001000b9010 in PyEval_EvalCodeEx ()
#30 0x00000001000b6ffd in PyEval_EvalFrameEx ()
#31 0x00000001000b9010 in PyEval_EvalCodeEx ()
#32 0x00000001000b6ffd in PyEval_EvalFrameEx ()
#33 0x00000001000b745a in PyEval_EvalFrameEx ()
#34 0x00000001000b9010 in PyEval_EvalCodeEx ()
#35 0x00000001000b6ffd in PyEval_EvalFrameEx ()
#36 0x00000001000b9010 in PyEval_EvalCodeEx ()
#37 0x00000001000b6ffd in PyEval_EvalFrameEx ()
#38 0x00000001000b9010 in PyEval_EvalCodeEx ()
#39 0x00000001000b6ffd in PyEval_EvalFrameEx ()
#40 0x00000001000b9010 in PyEval_EvalCodeEx ()
#41 0x00000001000b90f6 in PyEval_EvalCode ()
#42 0x00000001000dde0e in PyRun_FileExFlags ()
#43 0x00000001000de0c9 in PyRun_SimpleFileExFlags ()
#44 0x00000001000eb5eb in Py_Main ()
#45 0x0000000100000f14 in start ()
(gdb)
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10250>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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