How can I plot the periodic function? please help

how can I plot(t,Tg) or interpret Tg in t=(0:0.001:0.1n),n is a given positive integer ?

I had tried to modify the code in https://www.mathworks.com/matlabcentral/answers/163582-how-to-plot-a-piecewise-periodic-function-please-help

but it didn't work. plz help.

Answer 1

[Walter Roberson]

Tg = 2900 * size(t);
tmod = mod(t, 0.1);
mask = tmod > 0.007;
Tg(mask) = A * exp(-B * tmod(mask));

[PIN RUI HUANG]

How could I plot this? I used plot(t,Tg), it showed this message:

Error using plot

Vectors must be the same length.

[Torsten]

Replace

Tg = 2900 * size(t);

by

Tg = 2900 * ones(size(t));

[PIN RUI HUANG]

Thanks, Torsten and Walter Robinson.

Answer 2

[mousa alsaeed]

here is a code for a function that can give you the plot for any periodic function first thing you need to define a variable t as symbolic variable

syms t 

second thing define your function

f = log(t)-t 

the function needs a period and a specific number of cycles to draw your function in

T = 3; , N = 10;

here is the code for the function :

% done by mousa alsaeed 
% email : [e-mail]


function periodic(fun,period,number_of_cycles)

fp = 0;

syms t

for i=0:number_of_cycles-1
    
fp =  fp + subs(fun,t,(t-i*period))*(heaviside(t-i*period)-heaviside(t-(i+1)*period));
        
end   


fplot(fp,[0 number_of_cycles*period])
grid on
title('the periodic function')
xlabel('t')
set(gca,'XMinorTick','On','YMinorTick','On');


end

here is what you gonna write on the commmand window :

periodic(f,T,N)

and here is the results :

[Nabeel Bakr]

Dear Mr. Mousa Alsaeed,

My B.Sc. students are doing their B.Sc. graduation project about Fourier series using Matlab platform.

We came across your nicely written Matlab code which plots any periodic function.

We would be grateful if you kindly send us a modified version of your code so that it can plot the functions starting from the negative side of x-axis (i.e. from -N/2*T to N/2*T).

We plotted the function y=x^2 (T=2) and (N=3) using different procedure. (An image is attached).

But we would like to try your code.

With our best regards.

Stay Safe.

[mousa alsaeed]

sorry for the delay

same inputs as before and here is the new code that plots periodic function to be symmetric around the y-axis (i.e. starts from -N/2*T to N/2*T)

% done by mousa alsaeed 
% email : [e-mail]
function periodic(fun,period,number_of_cycles)
fp = 0;
syms t
for i= -number_of_cycles/2 : number_of_cycles/2
    
fp =  fp + subs(fun,t,(t-(2*i+1)*0.5*period))*(heaviside(t-i*period)-heaviside(t-(i+1)*period));
        
end   
fplot(fp,[(-number_of_cycles/2)*period (number_of_cycles/2)*period])
grid on
title('the periodic function')
xlabel('t')
set(gca,'XMinorTick','On','YMinorTick','On');
end

here is the results

[Nabeel Bakr]

Thank you very much for your help ... Regards