## POLY Convert Roots To Polynomial Coefficients

Section: Optimization and Curve Fitting

### Usage

This function calculates the polynomial coefficients for given rootsp = 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