Error using quad (line 70)

i write this code for value V=0 i see this error

clc; clear all;
n=10; t=-2.66; E0=0; eta=15*10^(-2); KbT=0.0258; Ef=0;  
alphag=1; alphad=0.5; Vg=0; U=0; j=0; phi=0; a0=1.42; a=1; b=1;
sigmaR=zeros(6,6);
sigmaL=zeros(6,6);
%E=-10:2*10/n:10;
kx=-pi/(3*a0); %:pi*2/(3*a0*100):pi/(3*a0)
%a=exp(-i*kx*a0/2); 
%b=exp(i*kx*a0);
V=0;
syms E;
UL=0;
%UL=-(alphag*Vg)-(alphad*V(l));
mu1=Ef;
mu2=Ef-V;
Hc=[E+i*eta-E0 -b*t 0 -a*t 0 0;-b'*t E+i*eta-E0 -a'*t 0 0 0; 0 -a*t E+i*eta-E0 0 0 -a*t; -a'*t 0 0 E+i*eta-E0 -a'*t 0; 0 0 0 -a*t E+i*eta-E0 -b*t; 0 0 -a'*t 0 -b'*t E+i*eta-E0]; 
sigmaR(3,3)=(-t)*exp(i*kx*a0);
sigmaL(4,4)=(-t)*exp(i*kx*a0);
gamaR=i*(sigmaR-sigmaR');
gamaL=i*(sigmaL-sigmaL');
Gc=inv(Hc-sigmaR-sigmaL);
T=trace(gamaR*Gc*gamaL*Gc');
f1=1./(1+exp((E+UL-mu1)));
f2=1./(1+exp((E+UL-mu2)));
I=T.*(f1-f2);
current=quad(vectorize(I),-10,10)

Error using quad (line 70)
The integrand function must return an output vector of the same length as the input vector.

Error in test (line 26)
     current=quad(vectorize(I),-10,10)

[John D'Errico]

What is I?

I
I =
0

I is a scalar. It is not even a function. The last time I checked, the integral of 0 over pretty much any interval you want is still ero. As for why you are using the old quad code, I have no idea, but even quad would be able to integrate it, if you actually provided a function.

A numerical integration tool must be passed a FUNCTION. Not a scalar, ot even a vector. If that is what you wanted to do, then use trapz or cumtrapz.

[Maedeh Mashhadbani]

i used int but it didnt work i try quad and it workes i dont know why int didnt work