The Polynomial Toolbox for MATLAB - DCE FEL ČVUT v Praze

The Polynomial Toolbox for MATLAB - DCE FEL ČVUT v Praze The Polynomial Toolbox for MATLAB - DCE FEL ČVUT v Praze

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2 Polynomial matrices Introduction In this chapter we review in a tutorial style many of the functions and operations defined for polynomials and polynomial matrices. This exposition continues in Chapter 3 Discrete-time and two-sided polynomial matrices. Chapter 5 is devoted to next objects, Polynomial matrix fractions. Functions and operations for linear timeinvariant systems defined by polynomial matrix fractions are discussed in Chapter 6, LTI systems. Chapter 6, Control system design covers the applications of polynomial matrices in control system design. More detailed information is available in Chapter 12, Objects, properties, formats and in the manual pages included in the companion volume Commands. Polynomials and polynomial matrices Polynomials are mathematical expressions of the form 2 n P s P0 Ps 1 P2 s Pn s where P0 , P1 , P2 , , P n are real or complex numbers, coefficients, and s is the indeterminate variable. Matrix polynomials are of the same form but with P0 , P1 , P2 , , P n numerical matrices, coefficients matrices. Alternatively and usually, these objects can be viewed as polynomial matrices, i.e. matrices whose individual entries are polynomials. These two concepts will be used interchangeably. For system and control engineers, s may be treated as the derivative operator d dt acting on continuous-time signals xt . It can be also considered as the Laplace transform complex variable. Entering polynomial matrices Polynomials and polynomial matrices are most easily entered using one of the indeterminate variables s, p that are recognized by the Polynomial Toolbox, combined with the usual MATLAB conventions for entering matrices. Thus, typing P = [ 1+s 2*s^2 2+s^3 4 ]

The pol command The Polynomial Matrix Editor The default indeterminate variable defines the matrix 2 1s 2s Ps () 3 2s4 and returns P = 1 + s 2s^2 2 + s^3 4 For other available indeterminate variables such as z, q, z^–1 or d see Chapter 3, Discrete-time and two-sided polynomial matrices. Polynomials and polynomial matrices may also be entered in terms of their coefficients or coefficient matrices. For this purpose the pol command is available. Typing P0 = [1 2;3 4]; P1 = [3 4;5 1]; P2 = [1 0;0 1]; P = pol([P0 P1 P2],2,'s') for instance, defines the polynomial matrix P = according to 1 + 3s + s^2 2 + 4s 3 + 5s 4 + s + s^2 P( s) P0 P1s P2 s 2 More complicated polynomial matrices may be entered and edited with the help of the Polynomial Matrix Editor (see Chapter 4). Note that if any of the default indeterminates is redefined as a variable then it is no longer available as an indeterminate. Typing s = 1; P = 1+s^2 results in

2 <strong>Polynomial</strong> matrices<br />

Introduction<br />

In this chapter we review in a tutorial style many of the functions and operations<br />

defined <strong>for</strong> polynomials and polynomial matrices. This exposition continues in<br />

Chapter 3 Discrete-time and two-sided polynomial matrices. Chapter 5 is devoted to<br />

next objects, <strong>Polynomial</strong> matrix fractions. Functions and operations <strong>for</strong> linear timeinvariant<br />

systems defined by polynomial matrix fractions are discussed in Chapter 6,<br />

LTI systems. Chapter 6, Control system design covers the applications of polynomial<br />

matrices in control system design.<br />

More detailed in<strong>for</strong>mation is available in Chapter 12, Objects, properties, <strong>for</strong>mats and<br />

in the manual pages included in the companion volume Commands.<br />

<strong>Polynomial</strong>s and polynomial matrices<br />

<strong>Polynomial</strong>s are mathematical expressions of the <strong>for</strong>m<br />

<br />

2<br />

n<br />

P s P0 Ps 1 P2 s Pn s<br />

where P0 , P1 , P2 , , P n are real or complex numbers, coefficients, and s is the<br />

indeterminate variable.<br />

Matrix polynomials are of the same <strong>for</strong>m but with P0 , P1 , P2 , , P n numerical matrices,<br />

coefficients matrices. Alternatively and usually, these objects can be viewed as<br />

polynomial matrices, i.e. matrices whose individual entries are polynomials. <strong>The</strong>se<br />

two concepts will be used interchangeably.<br />

For system and control engineers, s may be treated as the derivative operator d dt<br />

acting on continuous-time signals xt . It can be also considered as the Laplace<br />

trans<strong>for</strong>m complex variable.<br />

Entering polynomial matrices<br />

<strong>Polynomial</strong>s and polynomial matrices are most easily entered using one of the<br />

indeterminate variables s, p that are recognized by the <strong>Polynomial</strong> <strong>Toolbox</strong>, combined<br />

with the usual <strong>MATLAB</strong> conventions <strong>for</strong> entering matrices. Thus, typing<br />

P = [ 1+s 2*s^2<br />

2+s^3 4 ]

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