POLY Convert Roots To Polynomial Coefficients

Usage

This function calculates the polynomial coefficients for given roots

    p = poly(r)

when r is a vector, is a vector whose elements are the coefficients of the polynomial whose roots are the elements of r. Alternately, you can provide a matrix

    p = poly(A)

when A is an N x N square matrix, is a row vector with N+1 elements which are the coefficients of the characteristic polynomial, det(lambda*eye(size(A))-A). Contributed by Paulo Xavier Candeias under GPL.

Example

Here are some examples of the use of poly

--> A = [1,2,3;4,5,6;7,8,0]

A = 

 1 2 3 
 4 5 6 
 7 8 0 

--> p = poly(A)

p = 

    1.0000   -6.0000  -72.0000  -27.0000 

--> r = roots(p)

r = 

   12.1229 
   -5.7345 
   -0.3884