Hey guys,im following a textbook example which involves matrices.

Basically variables N1, N2, N3 and N4 and their derivatives are given by the following..


(These arent matrices, just corresponding values)

I need to calculate a 2x2 matrix called the jacobian (J) which is given by..



where for my problem..

x1 = 0
x2 = 6
x3 = 20
x4 = 0
y1 = 5
y2 = 5
y3 = 12
y4 = 12

The textbook gives an answer for J as..



but I get..



i.e. two of the values are reversed.

Don't suppose anyone could clear up whether I'm right or wrong?I'm using MATLAB and still getting my answer.

Any help would be greatly appreciated.

Mark.