Hi
thanks for your earlier answers.
I quite often do this:
sage: solve(x^3 + 10*x^2+11*x+8==0,x)
[snip]
Then I realize that the analytic solution is rather complicated.
So I want a numerical approximation.
I tried this:
roots = solve(x^3+10*x^2+11*x+8==0,x)
sage: roots
[x == -1/2*(1/3*sqrt(926) - 613/27)^(1/3)*(I*sqrt(3) + 1) -
1/18*(-67*I*sqrt(3) + 67)/(1/3*sqrt(926) - 613/27)^(1/3) - 10/3, x ==
-1/2*(1/3*sqrt(926) - 613/27)^(1/3)*(-I*sqrt(3) + 1) -
1/18*(67*I*sqrt(3) + 67)/(1/3*sqrt(926) - 613/27)^(1/3) - 10/3, x ==
(1/3*sqrt(926) - 613/27)^(1/3) + 67/9/(1/3*sqrt(926) - 613/27)^(1/3) -
10/3]
sage: N(roots)
but this returns an error ("too many values to unpack").
The best I can do is
N(roots[1].rhs())
but this is just one at a time. How do I make N() operate on all of roots?
Or is there a much neater way of accomplishing the same thing?
cheers
rksh
--
Robin Hankin
Uncertainty Analyst
hankin.ro...@gmail.com
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