Error using plot. Data must be numeric, datetime, duration or an array convertible to double.

I have the following code I obtained from a function:

syms n t
A0 = 5/4;
An= 0;
Bn = (5*(-1)^n)/(n*pi);
T = 2;
Wo = pi;

Arm = 5;

for n=1:1:Arm
    syms t
    f(n,:) = sum ((A0) + (An * cos(n*t)) + (Bn * sin (n*t)));
    t=linspace(0,5*T,1000);
    subplot(2,1,1);
    plot(t,subs(f(n,:), 't', t));
    grid on
    xlabel('\bfTIEMPO');
    ylabel('\bfAMPLITUD');
    title('\bfCOMPONENTE');
    hold on
    
    subplot(2,1,2);
    plot(t, subs(sum(f), 't', t), 'r', 'Linewidth', 1.5);
    xlabel('\bfTIEMPO');
    ylabel('\bfAMPLITUD');
    title('\bfSERIE DE FOURIER');
    pause(1)
end

I got the Fourier coefficients and now I want to graph these results, but I'm getting the following error:

Error using plot

Data must be numeric, datetime, duration or an array convertible to double.

Error in Armonico_Fourier_Proyecto_parcial1 (line 16)

plot(t,subs(f(n,:), 't', t));

I'm really newbie into MATLAB, any help will be greatly appreaciated.

Answer 1

[VBBV]

% syms n 
A0 = 5/4;
An= 0;
T = 2;
Wo = pi;
t=linspace(0,5*T,1000);
Arm = 5;
hold on
for n=1:1:Arm
    Bn = (5*(-1)^n)/(n*pi);
    f(n,:) =  (An * cos(n*t)) + (Bn * sin (n*t));  
    figure(1)
    plot(t,f(n,:));
    grid on
    xlabel('\bfTIEMPO');
    ylabel('\bfAMPLITUD');
    title('\bfCOMPONENTE');      
end

figure(2)
plot(t, A0+sum(f), 'r', 'Linewidth', 1.5);
xlabel('\bfTIEMPO');
ylabel('\bfAMPLITUD');
title('\bfSERIE DE FOURIER');

[VBBV]

The error suggests that you are trying to use symbolic variable for plot function. But plot function uses numeric arrays to graph, Further info how to use plot function can be found below link

https://in.mathworks.com/help/matlab/ref/plot.html

if you want to plot symbolic expressions, try using fplot

https://in.mathworks.com/help/matlab/ref/fplot.html

Answer 2

[Torsten]

Arm = 5;
T = 2;
t = linspace(0,5*T,1000);
t = t.';
hold on
for N=0:Arm
    n = 1:N;
    A0 = 5/4*ones(size(t));
    An= 0*ones(size(t));
    Bn = (5*(-1).^n)./(n*pi);
    f = A0 + sum (An.*cos(n.*t) + Bn.*sin(n.*t),2);
    plot(t,f)
end
hold off
grid on