How to find the Determinant of a Matrix

First let's look at a 2x2 matrix.  This is the easiest to do.

How did we do this?  Well, first step is to multiply the two values on the main diagonal, 1 x 4 = 4.  Then from that value we subtract the product of the other two values, in this case that means, 4 - (2x3) = -2.  Easy enough.

  

Now let's make it a tad more complicated and take the determinant of a 3x3 matrix.    

It's not too bad, you just have to keep your terms straight and the calculation should come out fine.  

Let's name the above 3x3 matrix A.  To find |A| in Matlab all you do is:

d = det(A)