A characteristic polynom that is generated by the procedure charpoly() has the type:
sage.rings.polynomial.polynomial_ring.PolynomialRing_field_with_category.element_class.
How can I convert it to one of type 'symbolic expression' without doing 'copy and paste'?
You can use the
sage: SR
Symbolic Ring
to convert the expression you get:
sage: m = random_matrix(ZZ, 3, 3)
sage: p = m.charpoly()
sage: type(p)
<type 'sage.rings.polynomial.polynomial_integer_dense_flint.Polynomial_integer_dense_flint'>
sage: SR(p)
x^3 + 2*x^2 - 8*x + 5
sage: type(_)
<type 'sage.symbolic.expression.Expression'>
Make sure you really need the symbolic ring. In many cases, you can get what you want more efficiently without converting to symbolic ring.
Thank you very much for the hint. I need the conversion to SR in order to simplify the expression with canonicalize_radical() or with factor(). This seems not be possible if I apply them on the unconverted expression (unimplemented error or attribute error). I just found that characteristic polynomals of matrices can also be converted to SR by substituting one of their symbols with subs.
I just found that characteristic polynomals of matrices can also be converted to SR by substituting one of their symbols with subs.
Asked: 2018-06-03 19:33:33 +0200
Seen: 468 times
Last updated: Jun 04 '18
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