I need to plot the first six partial sums of a fourier series. returning "error using plot" when I try

I am trying to calculate the first six partial sums of a piecewise function using a fourier series and plot their approximations on six separate sub plots. I am almost there but now when I try to plot the partial on the interval I previously defined I am returning the errors:

Error using plot

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

Error in q1t (line 34)

subplot (3, 2, n), plot(t,orig, t, f, '--')

my code is also included. any help is much appreciated

clc
clear
syms x;
f1=(1+x);
f2=1;
p=1;
orig=0;
a0=(1/p)*(int(f1,x,-1,0)+int(f2,x,0,1));
N=6;
for n=1:N
an=(1/p)*(int(f1*cos(n*pi*x/p),x,-1,0)+int(f2*cos(n*pi*x/p),x,0,1));
bn=(1/p)*(int(f1*sin(n*pi*x/p),x,-1,0)+int(f2*sin(n*pi*x/p),x,0,1));
orig=orig+(an*cos(n*pi*x/p)+bn*sin(n*pi*x/p));
end

t=linspace(-1,1); % create time points in plot
f= zeros (size(t)); % initialize function f (t)
for k = 1:length(t) % construct function f (t)
if t(k)<=0; f(k)=t(k)+1;end;
if t(k)>0; f(k) = 1;end;
end
% initialize fourier series with the mean term
orig = (a0/2)*ones(size(t));
clf % clear any figures
w=(int(f1*cos(n*pi*x/p),x,-1,0));
q=(int(f1*cos(n*pi*x/p),x,-1,0));
e=(int(f1*sin(n*pi*x/p),x,-1,0));
r=(int(f2*sin(n*pi*x/p),x,0,1));
for n = 1:6
% create plot of truncated FS with only n harmonic
an=(1/p)*(w+q);
bn=(1/p)*(e+r);
orig=orig+(an*cos(n*pi*x/p)+bn*sin(n*pi*x/p));
subplot (3, 2, n), plot(t,orig, t, f, '--')
if n==1
legend ('mean plus 1 term','f (t)'); legend boxoff;
else
legend(['mean plus ',num2str(n),'terms'],'f(t)')
legend boxoff
end
if n >= 5; xlabel('t'); end;
end