Need matlab code for sine function

[rizwan12]

HI everyone.

I want to plot a signal of sine wave with a frequency of 0.1 hz with an amplitude of -50 to 50 and time interval of 0 to 3500.can any anoe help me plz
regards
Rizwan

 

[BradtheRad]

When you say time interval of 3500, does that mean you have 3500 time steps per cycle? Then your frequency of 0.1 Hz is a cycle every ten seconds, and each time step is .00286 seconds.

Here is how I would write a routine in BASIC programming language.

(2 * Pi is one cycle in radian-based trig calculations as commonly used in computer routines.)

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Code Basic4GL - [expand]
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FOR div = 0 to 3500
 
A = 2 * Pi * div / 3500
 
B = SINE ( A )
 
amplitude = B * 50
 
elapsedtime = 10 * div / 3500
 
PRINT div, elapsedtime, amplitude
 
NEXT div

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Of course you will scale the plot values to fit your screen.

 

[thylacine1975]

Hiya Rizwan,

Like Brad, I'm not sure what you mean by a "time interval of 0 to 3500"..? If I interpret your requirement as "for a time interval of 3500 [seconds]", then a suitable MATLAB snippet could be:

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Code C - [expand]
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tD = 3500;      % [s]  Time duration
f  = 0.1;       % [Hz] Sine frequency
A  = 50;        % [-]  Dimensionless peak amplitude
 
Fs = 10;        % [Hz] Sampling frequency
 
t = 0:(1/Fs):(tD-1/Fs);  % Construct a vector of sampling 'instants' over the specified duration
 
sinOut = A*sin(2*pi*t*f);
 
% Plot it!
figure;          
plot (t, sinOut);
ylim([-A-10 A+10]);
title(['A ' num2str(f) ' Hz sine wave over ' num2str(tD) ' seconds.']);
xlabel('Time [seconds]')
ylabel('Amplitude');
grid on;

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The only extra thing I had to specify was a 'sampling frequency' (Fs) - or how often we calculate (and plot) a point over your 3500 second interval. The Nyquist criterion demands that Fs must be at least twice the signal of interest (0.1 Hz), so while anything > 0.2Hz would work, I chose 10 [Hz] to make it all look pretty (and PC memory's cheap

To zoom in on the plot without disturbing your vertical scale (which I've set to something aesthetically pleasing via the ylim([ ]) command), right click in the figure and select 'Horizontal zoom only'.

Cheers