m-file function for solving high order polynomial equation

I want to build for solving polynomial equation for high order (example x^202+x^102+x^52+100) and apply other problem.

I write m-file in this form.

function [eig] = solvepoly(chareq)

eq = 'chareq';
eig = solve(eq);

end

Then I use this function. The answer isn't correct.

>> [eig] = solvepoly(@(x) x^2+2*x+1)

eig =

0

But I use this command in command window. I get this answer.

>> eq = 'x^2+2*x+1'; >> eig = xolve(eq)

eig =

-1 -1

Help me please.

Answer 1

[Star Strider]

This is easier:

syms x
p = x^202+x^102+x^52+100;

r  = roots(sym2poly(p));

The ‘r’ variable will have all 202 roots.

[Panitnart]

I follow your suggestion in this m-file

function [r] = solvepoly(chareq)

syms x;
p = chareq;
r  = roots(sym2poly(p));

end

and try to command window

>> [r] = solvepoly(@(x) x^2+2*x+1)

Undefined function 'sym2poly' for input arguments of type 'function_handle'.

Error in solvepoly (line 5) r = roots(sym2poly(p));

[Star Strider]

I didn’t use an anonymous function in my code.

Since you did, all you need to do is to cast it as a symbolic function (using the sym function) and my code works just as well.

Try this:

p = @(x) x^202+x^102+x^52+100;

ps = sym(p);

r  = roots(sym2poly(ps));

[Panitnart]

I try to follow your suggestion. It's work.

Thank you very much for advice.

[Star Strider]

My pleasure!

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