How can the individual samples be visable in the plot

Like sin(2*pi*100*t) and t is between 0-0.5S, how could there be 25 samples?

Answer 1

[Image Analyst]

OK, I have a second answer. Maybe your "S" is not a value when you say 0.5S. Maybe "S" really means " seconds". In that case, try this:

% Demo by Image Analyst
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 25;
fprintf('Beginning to run %s.m ...\n', mfilename)

% Like sin(2*pi*100*t) and t is between 0-0.5S, how could there be 25 samples?
numSamples = 25;
t = linspace(0, 0.5, numSamples);
y = sin(2 * pi * 100 * t);
plot(t, y, 'b.-', 'LineWidth', 3, 'MarkerSize', 40);
grid on;
title('y = sin(2 * pi * 100 * t)', 'FontSize', 18);
xlabel('time in seconds', 'FontSize', 18);
ylabel('y', 'FontSize', 18);

g = gcf;
g.WindowState = 'maximized'
fprintf('Done running %s.m.\n', mfilename)

[Yian Chen]

Hi, thanks for your answer, and s do mean second, if I want my samples defined from 0 to 0.5s but does not include 0.5s, how can I make it?

[Image Analyst]

Just change to

t = linspace(0, 0.49999999999, numSamples);

or you can set the range of x in the plot with xlim(), like to see from 0 to 0.4, use

xlim([0, 0.4]);

Answer 2

[Image Analyst]

Here, try this:

% Demo by Image Analyst
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 25;
fprintf('Beginning to run %s.m ...\n', mfilename)

% Like sin(2*pi*100*t) and t is between 0-0.5S, how could there be 25 samples?
S = 100; % Whatever S is (we don't know because you didn't specify)
numSamples = 25;
t = linspace(0, 0.5 * S, numSamples);
y = sin(2 * pi * 100 * t);
subplot(2, 1, 1)
plot(t, y, 'b.-', 'LineWidth', 3, 'MarkerSize', 30);
grid on;
title('y = sin(2 * pi * 100 * t) with 25 samples (it is badly aliased)', 'FontSize', 18);
xlabel('t', 'FontSize', 18);
ylabel('y', 'FontSize', 18);

% We have bad aliasing.  Let's see what it looks like without aliasing.
numSamples = 2000;
t2000 = linspace(0, 0.5 * S, numSamples);
y2000 = sin(2 * pi * 100 * t2000);
subplot(2, 1, 2)
plot(t2000, y2000, 'r.-', 'LineWidth', 1);
grid on;
title('y = sin(2 * pi * 100 * t) with 2000 samples', 'FontSize', 18);
xlabel('t', 'FontSize', 18);
ylabel('y', 'FontSize', 18);

g = gcf;
g.WindowState = 'maximized'
fprintf('Done running %s.m.\n', mfilename)