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

Hi guys, I've been having an issue with trying to plot a function but I keep getting the error in the title. I've found some work arounds such a redefining t in section 3.4 with 't = 1:10' however that makes the output wrong. Any help would be appreciated.

%  Clearing and preparing the workspace
clear; clc; close all;

load Data1A;  

Fs = 44100;
y = noiseSound;
%soundsc(y,Fs);
T = 5;
numreps = 20;
%%A3.2

y_wave= ones(1,Fs/2);
y1 = ([-5*y_wave 6*y_wave]);
% repetitions of for the period
s = repmat(y1, ([1,numreps]));
%Making sure that an appropriate time domain vector t was generated for this waveform.Time vector goes from 0 to 20 seconds
t = linspace(0,numreps*T, numreps*Fs + 1);
t = t(1:end - 1);
x = 3 + 3.*t - t.^2;
%Saving  this to the variable additive_noise
additive_noise = repmat(y,1,20);

plot(t,y)
xlabel('Time')
ylabel('Audio Signal')

%%A3.3
syms n t
w0=pi; n = 1:10;

a0 = (1/5)*int(3+3*t-t.^2,t,0,5);
an = (2/5)*int((3+3*t-t.^2)*((cos(2*w0*n*t))/5),t,0,5);
bn = (2/5)*int((3+3*t-t.^2)*((sin(2*w0*n*t))/5),t,0,5);

%%A3.4

n = 1:10;
f0 = 1/5;

x = a0 + (an.*cos(2*pi*n*5.*t) + bn.*sin(2*pi*n*5.*t));

syms n 
FS1 = symsum(x, n, 1, 10);
    FS1 = repmat(FS1, [1,numreps]);

hold on
plot(t,FS1)
title('Figure1 - A2.1')
xlabel('Time')
ylabel('Audio Signal')
legend('Fourier Series Approximation')
hold off

Answer 1

[KSSV]

In section A3.3 you have defined t as a symbolic variable. You cannot plot symbolic variable. You need to transfer it into double using double.

[potplant]

I get a new error saying

Error using symengine
DOUBLE cannot convert the input expression into a double array.

Error in sym/double (line 616)
        Xstr = mupadmex('symobj::double', S.s, 0);

Error in mission (line 64)
double = double(t);

What I used is:

double = double(t);

[KSSV]

Yes it is...because still t is a symbolic variable. You have not assigned any values to it. If t values are same as defined in section A3.2, you define it again before plotting or use some other variable as syms t instead of t

[potplant]

I tried appending t to syms n before the FS1 function but that didn't work either. By defining it again do you simply mean just copy what I had in A3.2 into A3.4 like shown below? I'm not sure what you mean by I need to define it again, I'm not awfully good at this program.

%%A3.4
n = 1:10;
f0 = 1/5;

t = linspace(0,num_reps*T, num_reps*Fs + 1);
t = t(1:end - 1);

x = a0 + (an.*cos(2*pi*n*5.*t) + bn.*sin(2*pi*n*5.*t));

syms n
FS1 = symsum(x, n, 1, 10);
    FS1 = repmat(FS1, 10);

hold on
plot(t,FS1,'black')
title('Figure1 - A2.1')
xlabel('Time')
ylabel('Audio Signal')
legend('Fourier Series Approximation')
hold off

[suharsh tyagi]

Use the fplot function instead, to plot the symbolic functions.

[lenin sanchez]

thanks,that worked