#17785: crash in matrix.subs
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Reporter: cnassau | Owner:
Type: defect | Status: new
Priority: critical | Milestone: sage-6.10
Component: algebra | Resolution:
Keywords: crash, SIGSEGV, substitution | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Changes (by vdelecroix):
* priority: minor => critical
* keywords: crash, substitution => crash, SIGSEGV, substitution
* milestone: sage-6.5 => sage-6.10
Old description:
> The following code gives a coredump in Sage-6.5.rc3:
> {{{
> a11,a12,a13,a21,a22,a23,a31,a32,a33 = allvars =
> var("a11,a12,a13,a21,a22,a23,a31,a32,a33")
> P=PolynomialRing(QQ,allvars,order='degrevlex')
> P.inject_variables()
> A=matrix([[a11,a12,a13,],[a21,a22,a23,],[a31,a32,a33]])
> A.subs(a11=a13,a21=-a23,a31=a33,a22=0)
> }}}
New description:
The substitution code for multipolynomial (using Singular) results in a
SIGSEV. For example, with `R.<x,y,z> = QQ[]` and any of
{{{
x.subs(None,y=x,x=0,z=y)
x.subs(None,x=0,y=x,z=x)
x.subs(None,x=0,y=0,z=x)
x.subs(None,x=0,y=0,z=z)
}}}
Though, if we do not mix integer and variable in the substitutions it
seems to work fine
{{{
sage: x.subs(None,x=0,y=0,z=0)
0
sage: x.subs(None,x=z,y=x,z=y)
z
sage: x.subs(None,x=x,y=y,z=z)
x
}}}
And the following also works
{{{
sage: x.subs(None,x=0,y=x,z=0)
0
sage: x.subs(None,x=0,y=y,z=0)
0
sage: x.subs(None,x=0,y=z,z=0)
0
sage: x.subs(None,x=y,y=z,z=0)
y
sage: x.subs(None,x=y,y=0,z=0)
y
sage: x.subs(None,x=z,y=0,z=0)
z
}}}
-------
Original report
The following code gives a coredump in Sage-6.5.rc3:
{{{
a11,a12,a13,a21,a22,a23,a31,a32,a33 = allvars =
var("a11,a12,a13,a21,a22,a23,a31,a32,a33")
P=PolynomialRing(QQ,allvars,order='degrevlex')
P.inject_variables()
A=matrix([[a11,a12,a13,],[a21,a22,a23,],[a31,a32,a33]])
A.subs(a11=a13,a21=-a23,a31=a33,a22=0)
}}}
--
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Ticket URL: <http://trac.sagemath.org/ticket/17785#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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