#6934: Fix eigenvectors (and a lot of other stuff) for symbolic matrices
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Reporter: kcrisman | Owner: was
Type: defect | Status: new
Priority: major | Milestone: sage-4.1.2
Component: linear algebra | Keywords: symbolics, matrices, polynomials
Reviewer: | Author:
Merged: |
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From sage-devel [http://groups.google.com/group/sage-
devel/browse_thread/thread/4f39037d7fd17133] we have the following:
{{{
sage: A=matrix(SR,[[1,2,3],[4,5,6],[7,8,9]])
sage: A.eigenvectors_right()
Traceback (most recent call last):
...
TypeError: degree() takes exactly one argument (0 given)
}}}
As it turns out, there are a HOST of things you can't do with A because of
the new symbolics, which no one has yet implemented. Another example:
{{{
sage: A = matrix(SR, [[1,2,3],[4,5,6],[7,8,9]])
sage: A.charpoly()
(x - 1)*((x - 9)*(x - 5) - 48) - 29*x - 3
sage: type(_)
<type 'sage.symbolic.expression.Expression'>
sage: B = matrix(QQ, [[1,2,3],[4,5,6],[7,8,9]])
sage: B.charpoly()
x^3 - 15*x^2 - 18*x
sage: type(_)
<class
'sage.rings.polynomial.polynomial_element_generic.Polynomial_rational_dense'>
}}}
which means minpoly does not work (because it requires a polynomial, not
an expression) and so on.
These were not caught before because these things were not tested, since
they weren't actually implemented in the dense symbolic matrix file.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6934>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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