Find the quadratic function with the roots of -2 and p

The roots routine will return a column vector containing the roots of a polynomial. The general syntax is

  z = roots(p)

where p is a vector containing the coefficients of the polynomial ordered in descending powers.

Given a vector

which describes a polynomial

we construct the companion matrix (which has a characteristic polynomial matching the polynomial described by p), and then find the eigenvalues of it (which are the roots of its characteristic polynomial)

Example

Here is an example of finding the roots to the polynomial

--> roots([1 -6 -72 -27])

ans =  

  12.1229  

  -5.7345  

  -0.3884