Csapi Coefficients in a n-dimensional spline

I am trying to understand the coefficients of a spline.

Basically based on the coefficients.

Given something like

      form: 'pp'
    breaks: {[1 2]  [1 2]}
     coefs: [1x2x2 double]
    pieces: [1 1]
     order: [2 2]
       dim: 1

I understand the order, pieces, however. How to interpret the coefficients. Take one piece equation to be: (x,y)

z(1piece) = c1*(x-1)*(y-1)^3+c2*(x-1)*(y-1)^2+c3*(x-1)*(y-1)+c4*(x-1)+c5*(y-1)^3+c6*(y-1)^2+c7*(y-1)+c8;

How do I map the c1 to the coefs? Would it be possible to have a table that can be visualized?

[Merged information from additional question]

Anyone knows how csapi manages its coefficients for 2 or 3 dimensions.

Answer 1

[Wolfgang]

You might want to check out my answer to a similar question at http://www.mathworks.com/matlabcentral/answers/77100-reconstruct-multivariate-spline-from-csapi#answer_90257.