I want to calculate roots of a polynomial whose coefficients are functions of x where x assume values between an interval

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ASHA RANI
ASHA RANI 2017-10-21
评论： ASHA RANI 2017-10-21
Let x =[0:1:10]; polynomial = [ 1 sin(x) x.^3 x]; let v1,v2 and v3 be the three roots of given polynomial in v whose coefficients are functions of x. I want to plot a graph between v1 and x.
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ASHA RANI
ASHA RANI 2017-10-21
编辑：Matt J 2017-10-21
> x = [0:pi/18:pi/6]
x =
0 0.1745 0.3491 0.5236
>> p = [1 sin(x) x.^3 x];
>> r = roots(p)
r =
0.8999 + 0.3217i
0.8999 - 0.3217i
0.6749 + 0.8031i
0.6749 - 0.8031i
0.2643 + 0.9220i
0.2643 - 0.9220i
-0.3081 + 0.8491i
-0.3081 - 0.8491i
-0.8635 + 0.2723i
-0.8635 - 0.2723i
-0.6675 + 0.6335i
-0.6675 - 0.6335i
in this ans of r, which one is represented v1 corresponding to pi/18?
John D'Errico
John D'Errico 2017-10-21
So why did you set x=pi/18?
You were asked to solve this problem for x varying from 0 to 10, NOT just at one value of x.
If the polynomial has three roots, what does v1 versus v2 and v3 mean? Roots need not be provided in any specific order. So how are you supposed to choose v1?

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Matt J
Matt J 2017-10-21
编辑：Matt J 2017-10-21
You cannot use ROOTS on multiple polynomials at a time. You will have to use a loop over x(i),
for i=1:numel(x)
p =[1 sin(x(i)) x(i).^3 x(i)];
r{i}=roots(p);
%More code...
end
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ASHA RANI
ASHA RANI 2017-10-21
thank you,sir I am sending my original problem in which I want to plot between v1 and corresponding x. please help it

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