How get the maximal positive root of polynomial?

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Asatur Khurshudyan
评论： Asatur Khurshudyan 2016-2-4
I have such a function which computes positive roots of 8th order polynomial.
function res = lambdazero1( l, a )
p = [-2 * l^4, 0, l^4 * (3 * a^2 - 2 * l^2 + 3), 0, 0, 0, l^2 * ( l^2 -3 * a^2 + a^6 * ( l^2-3 ) ), 0, 2 * a^6];
sol = roots(p);
res = sol(imag(sol) == 0 & sol > 0);
end
It turns out that for some values of "l" and "a" it has several positive roots. Any idea how to get the maximal positive root?
Many thanks in advance.

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采纳的回答

Torsten
Torsten 2016-2-4
Add
res = max(res)
in your code from above.
Best wishes
Torsten.

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