reflect

Reflect lag operator polynomial coefficients around lag zero

Syntax

B = reflect(A)


Description

Given a lag operator polynomial object A(L),B = reflect(A) negates all coefficient matrices except the coefficient matrix at lag 0. For example, given a polynomial of degree p,

$$A(L)=A_0+A_{1}L+A_2{L}^2+\mathrm{...}+A_P{L}^p$$

the reflected polynomial B(L) is

$$B\left(L\right)=A_0-A_{1}L-A_2{L}^2-\mathrm{...}-A_P{L}^p$$

with the same degree and dimension as A(L).

Examples

Reflect a Lag Operator Polynomial

Create a LagOp polynomial and its reflection:

A = LagOp({0.8 1 0 .6});
B = reflect(A)

B = 
    1-D Lag Operator Polynomial:
    -----------------------------
        Coefficients: [0.8 -1 -0.6]
                Lags: [0 1 3]
              Degree: 3
           Dimension: 1