Plotting polynomial values at given points.

I want to find the roots of Wilkinson polynomial and then compute the values of this polynomial for these roots. Everytning goes fine until I try to plot the values for my roots. I get: "Error using plot. Vectors must be the same lengths" How can I fix it? This what I wrote:

 syms x;
 P20 = prod(x-(1:n));
 P = expand(P20);
 z = roots(p);
 y = poly (z);
 fmt = '%25.16f\n';
 fprintf(fmt,z),
 plot (z,y)

Answer 1

[pragnan nadimatla]

As per my understanding,you are encountering an error while trying to plot the roots of Wilkinson polynomial.In this case,the potential cause behind the error is that you are not specifying the X-Values for the polynomial.

Please refer below for the corrected version of code.

syms x;
n = 20;
P20 = prod(x-(1:n));
P = expand(P20);
z = roots(P);
fmt = '%25.16f\n';
fprintf(fmt,z);

% Evaluate the polynomial at 1000 points between -1.5 and 1.5
x_vals = linspace(-1.5, 1.5, 1000);
y_vals = subs(P, x_vals);

% Plot the polynomial and the roots
figure;
plot(x_vals, y_vals);

I hope the provided resolution helps!