Changes between Version 13 and Version 28 of Ticket #18787


Ignore:
Timestamp:
09/19/15 06:18:48 (4 years ago)
Author:
rws
Comment:

Replying to vdelecroix:

Why is it in sage-pending?

I didn't want patchbot on it.

Legend:

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  • Ticket #18787

    • Property Status changed from new to needs_work
    • Property Authors changed from to Ralf Stephan
    • Property Milestone changed from sage-6.8 to sage-6.9
    • Property Summary changed from Bug with products of symbolic variables with modular integers to symbolic modular integers still broken
    • Property Branch changed from to u/rws/bug_with_products_of_symbolic_variables_with_modular_integers
    • Property Commit changed from to 6f9e551e2110aa700b29eee6f379ec93890d7ba8
  • Ticket #18787 – Description

    v13 v28  
    1 As reported on [http://ask.sagemath.org/question/27196/multiplying-matrices-with-different-parents/ this ask question]
    2 
    3 {{{
    4 sage: _ = var('A,B')
    5 sage: (A + 3*B)*Zmod(9)(6)
    6 0*B
    7 }}}
    8 
    9 while the result should be `6*A`.
    10 
    11 It seems that the internal state of these objects is really messed up:
    12 {{{
    13 sage: _ = var('A,B')
    14 sage: (3*A + 3*B)*Zmod(9)(6)    # Yes, the output is really empty!
    15 
    16 sage: (3*A + 3*B)*Zmod(9)(6)*A 
    17 ------------------------------------------------------------------------
    18 Unhandled SIGSEGV: A segmentation fault occurred in Sage.
    19 This probably occurred because a *compiled* component of Sage has a bug
    20 in it and is not properly wrapped with sig_on(), sig_off().
    21 Sage will now terminate.
    22 ------------------------------------------------------------------------
    23 }}}
     1> {{{
     2> sage: f(x) = Zmod(7)(1) * x**2 + Zmod(9)(1) * x**3
     3> sage: f(1)
     4> 2
     5> sage: Zmod(7)(1) + Zmod(9)(1)
     6...
     7TypeError: unsupported operand parent(s) for '+': 'Ring of integers modulo 7' and 'Ring of integers modulo 9'
     8> }}}