[Insight-users] Size of Jacobian?

[motes motes]

I am using the BSplineDeformableTransform in a 2D registation application.

I am using a cubic BSpline, order=3 and have choosen to cover the
image with 5*5 nodes. The total nodes are 8*8 = 64 (3 boundary nodes
in each dimension). Since I am working in 2D I get 64*2=128
coefficients. And since I am using a third order BSpline I get
(3+1)*(3+1) = 16 weights for each pixel.

When I print the m_Jacobian:

  std::cout << "m_Jacobian size = " << m_Jacobian.size() << std::endl;

from the GetJacobian() function I get the size:

256.

I thought that the jacobian was a matrix with number of rows equal to
the dimension (2) and number of columns equal to the number of
parameters (128). But maybe  the two rows are just concatenated into a
flat array:

[x0,x1,x2,...,xN, y0,y1,...,yN]

like the parameters array?