If A is an N by N matrix, POLY(A) is a row vector with
N+1 elements which are the coefficients of the
characteristic polynomial, DET (lambda*EYE (A) - A) .
If V is a vector, POLY(V) is a vector whose elements are
the coefficients of the polynomial whose roots are the
elements of V . For vectors, ROOTS and POLY are inverse
functions of each other, up to ordering, scaling, and
ROOTS (POLY(1:20)) generates Wilkinson's famous example.
See also ROOTS7H4N0HR, POLYVAL .