POLY

Purpose:

Calculates coefficients of the characteristic polynomial.

Syntax:

POLY(x)

x

-

A series or matrix. A matrix where the eigenvalues are the roots of the returned polynomial coefficients or a series of the roots of the returned polynomial coefficients.

Returns:

A series, the polynomial coefficients in descending order.

Example:

W1: {{1, 2, 3},

     {3, 4, 5}, 

     {5, 6, 0}} 

W2: poly(W1)

W3: polyroot(W2, 1)

W4: eig(W1)

 

W2 contains the series {1, -5, -47, -14}, the coefficients in descending order of the characteristic polynomial of the matrix in W1. The roots of this polynomial are the eigenvalues of the input matrix.

 

W3 == {9.894, -4.585, -0.309}

W4 == {9.894, -0.309, -4.585}

Example:

If the input is a series, the input represents the roots of the polynomial coefficients returned by POLY. For example, consider the polynomial:

 

image\poly01.gif

 

poly({-2, -1}) == {1, 3, 2}

 

polyroot({1, 3, 2}, 1) == {-2, -1}

Remarks:

As indicated above, if the input is a matrix, POLY returns the coefficients of the characteristic polynomial in descending order.

 

If the input is a series, the input represents the roots of a polynomial and POLY returns the coefficients of this polynomial in descending order.

See Also:

EIG

POLYFIT

POLYDER

POLYINT

POLYROOT

POLYSTAB

POLYVAL

ROOTS