Preface (Communications Toolbox)

Communications Toolbox

Technical Conventions

This section mentions some technical conventions that this guide uses.

Polynomials as Vectors

MATLAB represents a polynomial in one variable x using a vector that lists the polynomial's coefficients, arranged according to the powers of x. Descending order means that the coefficient of the highest power of x appears first and that the polynomial's constant term appears last. Ascending order is the opposite. The table below illustrates the conventions for functions in this toolbox and for built-in MATLAB functions.

Category of Functions
Vector That Represents the Polynomial 1+2x+3x²

Error-control coding using Hamming, BCH, cyclic, or generic linear block codes
[1, 2, 3] (ascending order)

Computations in Galois fields of odd characteristic

Other functions in the Communications Toolbox
[3, 2, 1] (descending order)

Functions in MATLAB, such as roots and polyval

Category of Functions	Vector That Represents the Polynomial 1+2x+3x²
Error-control coding using Hamming, BCH, cyclic, or generic linear block codes	[1, 2, 3] (ascending order)
Computations in Galois fields of odd characteristic
Other functions in the Communications Toolbox	[3, 2, 1] (descending order)
Functions in MATLAB, such as `roots` and `polyval`

Matrices

Matrix dimensions are described by listing the number of rows and the number of columns of the matrix in that order, as below.

```
u = [1 2 3;4 5 6] % A 2-by-3 matrix
```

Configuration Information Typographical Conventions