Finding the determinant without det(a)

I need to physically computate the determinant of 3x3 matrices and lower without using the det(a) function, rather loops. What's causing this error?

[DGM]

Like Max, I'm guessing that matrix a1 isn't the expected size. In the future, it's best to post the code as formatted code instead of pictures so that people can troubleshoot it.

I'm just going to throw this out there. You can reuse the code for calculating the 2x2 case.

A = rand(3);

DA1 = det(A)

DA1 = 0.0476

DA2 = det33(A)

DA2 = 0.0476

function D = det22(A)
    D = prod(A([1 4])) - prod(A([2 3]));
end

function D = det33(A)
    D = A(1,1)*det22(A(2:3,2:3)) - A(1,2)*det22(A(2:3,[1 3])) + A(1,3)*det22(A(2:3,1:2));
end	

Answer 1

[Max Heimann]

According to the error you are trying to access an index which is not part of the variable.

Are you sure a1 is a 3x3 matrix?

It looks like you are calling the function with a 2x3 matrix [1 2 3; 4 5 6]

[Ryan Driver]

Stupid mistake. Thank you.