MATLAB: MATlab wont do integrate command

integrationMATLAB

Matlab only gives errors when the script is:

int(x)
%or

int(x,x)
%or
int(x+5,x)

I just want to get answers such as .5x^2, or .5x^2+5x.

The error is: Undefined function 'int' for input arguments of type 'double'.

I have Symbolic Math Toolbox Version8.2 (R2018b) running

You have to first initialize x as a symbolic variable. You can find more information and examples here.

syms x 
f = .5*x^2
int(f)

use the trapz function

source: help file

Both answers are correct.

d/dx[ (x+y)^2/2 ] = d/dx[ x^2/2 + x*y + y^2/2 ] = x + y

d/dx[ x^2/2 + x*y ] = x + y

The ambiguity lies in the constant of integration. In the first case the constant of integration ends up being y^2/2.

If you really want to enforce that the constant of integration is zero then do:

F = int(x+y,x,0,x)
expand(F)