And another observation:
maxima returns answer immediatelly (with a lag necessary to start
maxima)
m is the original matrix from x.py
sage: m._maxima_().determinant().expand().sage()
x0^2*x2^2*x3^2*x7^2 - 2*x0*x1*x2*x3*x4*x5*x6*x7 + x1^2*x4^2*x5^2*x6^2
Anyway, the answer is different from expected one. I do not konw which
one is correct.
Robert
On 17 pro, 11:40, "ma...@mendelu.cz" <ma...@mendelu.cz> wrote:
> perhaps problems expanding polynomials? even determinant of submatrix
> (0,0,5,5) is suprisingly slow.
>
> workaroud is to replace polynomials in your matrix by variables.
>
> var('x0 x1 x2 x3 x4 x5 x6 x7 a1 a2 a3 a4 a5 a6 a7 b1 b2 b3 b4 b5 b6
> b7')
> m=matrix([[ 0, a1, a2, a3, a4, a5, a6, a7],
> [b1, 0, x0, 0, 0, 0, 0, 0],
> [b2, x0, 0, x6, 0, 0, 0, 0],
> [b3, 0, x6, 0, x3, 0, 0, 0],
> [b4, 0, 0, x3, 0, x4, 0, 0],
> [b5, 0, 0, 0, x4, 0, x2, 0],
> [b6, 0, 0, 0, 0, x2, 0, x1],
> [b7, 0, 0, 0, 0, 0, x1, 0]])
> m
>
> m.det() gives answer immediatelly and you can substitute back for a's
> and b's.
>
--
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to
sage-support+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sage-support
URL: http://www.sagemath.org
