I try to plot these 2 graphs on the same plot but matlab return error 'can't divide by zero' and refer me to sinc of 0.  

I don't know what to do bc `sinc(0)=1`, I don't understand the problem.

**my code:**

```
syms x  
ezplot(heaviside(x+1) - heaviside(x-1), [-2, 2])  
hold  
t=-2:0.1:2;  
syms k  
r=symsum( ((sinc(k/2)/2)*exp((1i)*k*pi*(t/2))), -1,1);  
plot(t,r)  

```

**problem:**

```
  ??? Error: File: aa.m Line: 6 Column: 18
Unexpected MATLAB expression.

Current plot held
??? Error using ==> mupadmex
Error in MuPAD command: Division by zero [_power];

during evaluation of 'sum::sum'

Error in ==> sym.symsum at 74
   r = mupadmex('symobj::map',f.s,'symobj::symsum',x.s,a.s,b.s);

Error in ==> aa at 6
r=symsum( ((sinc(k/2)/2)*exp((1i)*k*pi*(t/2))), -1,1);

```