Undefined function using int function?

Hi, I've been trying to figure out how to use the int function to solve the area, but every time i use it and says ' Undefined function 'int' for input arguments of type 'double'. My version of MATLAB does not have the symbolic toolbox so I can not use syms x etc.

This is the equation I am working with, and here is my code I've generated so far;

close all
clc

N = 2; % No. of axles
Pnf = (2.5+2.05) * 9.81; % Weight of the point load in newtons
PnR = 2.05*9.81; %if the cart was split into two, 50% weight distrubition on the axles
Weight = 4.1*9.81;  % Weight of cart when empty
n = 1; 

Nn = N .* n;
e = cumsum(n);
en = cumsum(Nn);

tt = (Pnf .* e) + (PnR .* e);

GVW = tt/9.81 

% Now find a way to generate the Area of the callibrated data.
% The influence area, A, of a truck passing by... which is a result from
% the response wave.

% Distance between the axles, xn

xx = 3; % Distance to where the point load is, half the span of slot 4
xn = 0.6

Ap = GVW .* e;

aaaa = int((xx - xn),-Inf,Inf)

I am not entirely sure this has been the correct method or approach, would like to get some feedback please. Thank you.

[KSSV]

Read the documentation of int it accepts variables as inputs. You are giving double as inputs.

[Joshua]

Since you don't have symbolic functions, you might be able to use anonymous functions and the integral command as a work around. It would look something like this:

xn=0.6;
func=@(x) x-xn
integral(func,-inf,inf)

Not really sure I understand the summation portion of the problem though.