Introduction to MATLAB - Continuous and Discrete Time Signals and Systems - page 842

>> Ztran = X'; % Calculates transpose of X
% Returns [2 4; 5 6]
>> Zinv = inv(X); % Inverts X
% Returns [-0.75 0.62; 0.50 -0.25]
>> Zarraymul = X.*Y; % Element by element multiplication
% Returns [2 25; 24 -12]
>> Zarraydiv = X./Y; % Element by element division
% Returns [2 1; 0.6667 -3]

>> Zpower1 = X. ∧ 2; % Each element is raised to power

%by2
% Returns [4 25; 26 36]

>> Zpower2 = X. ∧ Y; % Each element in X is raised to

% power by its corresponding
% element in Y
% Returns [2 3125; 4096 0.028]

E.5 Plotting functio ns

M ATLAB supports multidimensional visualization that allows experimental
data to be rendered graphically in a comprehensible format. In this section, we
will focus on 2D plots for continuous-time and discrete-time variables. Readers
should check the demo for more advanced graphics including 3D plots.

Example E.7
Plot the following function:

f [ k ] = 2 cos(0 . 5 k )

as a function of k for the range − 20 ≤ k ≤ 20 .

Solution
The following set of M ATLAB instructions will generate and plot the function:

>> k = -20:20; % Initializes k as a (1 x 41)

% row vector

>> f = 2*cos(0.5*k); % Initializes f as cos(0.5k)

>> figure(1); % selects figure 1 where plot

% is drawn

>> plot(k,f); grid on; % CT plot of f (ordinate)

% versus k (abscissa)
% Grid is turned on

>> xlabel('k'); % Sets label of X-axis to k

>> ylabel('f[k]'); % Sets label of Y-axis to f[k]

>> axis([-25 25 -3 3]) % Plot is viewed in the range

% given by