Wrong matrix multiplication answer

Hi,

This multiplication gets a wrong answer:

E=[Eopt(1) 0];

coupler=[sqrt(0.9) 1i*sqrt(0.1);1i*sqrt(0.1) sqrt(0.9)];

Eout=coupler*E(1);

The answer:

Eout =

   9.4868 + 0.0000i  -0.0000 + 3.1623i
  -0.0000 + 3.1623i   9.4868 + 0.0000i

I am multiplying a 2x2 with a 2x1 matrix, so the result should be a 2x1 matrix.

Why is that?

Thanks

Answer 1

[Guillaume]

No, you are multiplying a 2x2 matrix with a scalar, the first element of E.

Did you mean?

Eout = coupler * E;

Answer 2

[Image Analyst]

E(1) is a scalar = just a single number. Try this:

Eopt = 3 % Whatever....
E=[Eopt(1) 0]
coupler=[sqrt(0.9) 1i*sqrt(0.1);1i*sqrt(0.1) sqrt(0.9)]
Eout= E * coupler  % E is now a matrix and on the left.