I want to multiply a matrix by its transposed in order to knwo if it verify Q^{t}Q=I.

Yet when I compute it on matlab I get something strange using a concept I'm not aware of: `conj(x)`

.

- Therefore, how to multiply a matrix by its transposed?

Here is the code I tried:

```
>> syms x
>> A=[cos(x) -sin(x);
sin(x) cos(x)]
A =
[ cos(x), -sin(x)]
[ sin(x), cos(x)]
>> A'*A
ans =
[ cos(conj(x))*cos(x) + sin(conj(x))*sin(x), sin(conj(x))*cos(x) - cos(conj(x))*sin(x)]
[ cos(conj(x))*sin(x) - sin(conj(x))*cos(x), cos(conj(x))*cos(x) + sin(conj(x))*sin(x)]
```