Matrix must be square error.

Hi. Im trying to find determinant of A. But I got this type of error. How to solve this and why do I get this error?

This is my code:

 function ret = detA(Ra)
      global k
      q0= 1i.*k.*(-1+(Ra./k^4)^(1/3))^(1/2);
      q1= k.*(1+(Ra./k^4)^(1/3).*(1/2+1i*sqrt(3)/2))^(1/2);
      q2= k.*(1+(Ra./k^4)^(1/3).*(1/2-1i*sqrt(3)/2))^(1/2);

      A=[1 1 1 1 1 1; 
         exp(q0) exp(-q0) exp(q1) exp(-q1) exp(q2) exp(-q2);
         q0 -q0 q1 -q1 q2 -q2; 
         q0.*exp(q0) -q0.*exp(-q0) q1.*exp(q1) -q1.*exp(-q1) q2.*exp(q2) -q2.*exp(-q2); 
        (q0.^2-k.^2).^2 (q0^2-k^2).^2 (q1^2-k^2).^2 (q1^2-k^2).^2 (q2^2-k^2)^2 (q2^2-k^2)^2; 
        (q0.^2-k.^2).^2.*exp(q0) (q0^2-k^2).^2.*exp(-q0) (q1^2-k^2).^2.*exp(q1) (q1^2-k^2).^2.*exp(-q1) (q2^2-k^2).^2.*exp(q2) (q2^2-k^2).^2.*exp(-q2)];

      ret=det(A);
      end

And i got this error:

Error using det
    Matrix must be square.
    Error in detA (line 14)
    ret=det(A);

Try Ra=1708.

[KSSV]

You should note that determinant exists for a square matrix only. For rectangular matrices, vectors you cannot find determinant. In your case when Ra = 1708..your A is a vector of size 1x6. So determinant does not exist for this..so error.

Answer 1

[Walter Roberson]

You did not initialize the global variable k. Uninitialized global variables are empty. Your q are calculated from k so they are empty.