Basic Manipulations of Galois Arrays :: Galois Field Computations (Communications Toolbox)

Communications Toolbox

Basic Manipulations of Galois Arrays

Basic array operations on Galois arrays are in the table below. The functionality of these operations is analogous to the MATLAB operations having the same syntax.

Operation	Syntax
Index into array, possibly using colon operator instead of a vector of explicit indices	`a(vector)` or `a(vector,vector1)`, where `vector` and/or `vector1` can be "`:`" instead of a vector
Transpose array	`a'`
Concatenate matrices	`[a,b]` or `[a;b]`
Create array having specified diagonal elements	`diag(vector)` or `diag(vector,k)`
Extract diagonal elements	`diag(a)` or `diag(a,k)`
Extract lower triangular part	`tril(a)` or `tril(a,k)`
Extract upper triangular part	`triu(a)` or `triu(a,k)`
Change shape of array	`reshape(a,k1,k2)`

The code below uses some of these syntaxes.

m = 4; a = gf([0:15],m);
a(1:2) = [13 13]; % Replace some elements of the vector a.
b = reshape(a,2,8); % Create 2-by-8 matrix.
c = [b([1 1 2],1:3); a(4:6)]; % Create 4-by-3 matrix.
d = [c, a(1:4)']; % Create 4-by-4 matrix.
dvec = diag(d); % Extract main diagonal of d.
dmat = diag(a(5:9)); % Create 5-by-5 diagonal matrix
dtril = tril(d); % Extract upper and lower triangular
dtriu = triu(d); % parts of d.

Matrix Manipulation in Galois Fields

Basic Information About Galois Arrays