Matlab roots help

I need help in generating 100 different polynomials of a certain degree and then finding the total number real roots. I know that I can generate a random polynomial of say degree 5 by typing

x=roots(rand([1 6]))

I also figured out the total number of real numbers by typing

size(x(imag(x)==0))

Can someone help me in writing a for loop for this?

Quote:

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Originally Posted by YankeesFan

I need help in generating 100 different polynomials of a certain degree and then finding the total number real roots. I know that I can generate a random polynomial of say degree 5 by typing

x=roots(rand([1 6]))

I also figured out the total number of real numbers by typing

size(x(imag(x)==0))

Can someone help me in writing a for loop for this?

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x=roots(rand([1 6]))

will not generate the polynomials and roots you want as all the coefficients will be positive and so before you start you have no positive roots.

Try:

x=roots(rand([1 6]-0.5))

CB

Quote:

---

Originally Posted by YankeesFan

I need help in generating 100 different polynomials of a certain degree and then finding the total number real roots. I know that I can generate a random polynomial of say degree 5 by typing

x=roots(rand([1 6]))

I also figured out the total number of real numbers by typing

size(x(imag(x)==0))

Can someone help me in writing a for loop for this?

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Basic for loop structure is:

Code:

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rv=zeros(1,100);
for idx=1:100
 
  %code to do what you want

  rv(idx)=...  ; % assign the idx-th element of the
                  % results vector to result for current
                  % loop trip
end

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CB