Numerical approximations
g(x)=x^2-sqrt(2)
solve(g(x)==0,x)
[x == -2^(1/4), x == 2^(1/4)]
What's the best/quickest way to get numerical approximations of these values of x? Thanks.
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3 Answers
Try taking the right hand side of each solution.
sage: A = solve(g(x)==0,x)
sage: [a.rhs().n() for a in A]
[-1.18920711500272, 1.18920711500272]
where n() is short for numerical_approx(). There are other ways of approaching this as well, such as via the solution_dict=True keyword to solve().
With my background neither is particularly straight-forward but I am happy to learn about both methods. Thanks.
In your case, since g can be seen as a polynomial, you can also look at its roots in the real double field (floating-point approximations with 53 bits of precision):
sage: g.polynomial(RDF).roots()
[(-1.189207115002721, 1), (1.189207115002721, 1)]
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Asked: 2015-06-04 01:33:02 +0100
Seen: 939 times
Last updated: Jun 05 '15
