xi

Tensor-product spline coefficients reshaped to basisSize.

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Discussion

The coefficient array weights the tensor basis in

\[f(x_1,\ldots,x_d) = x_{\mathrm{Mean}} + x_{\mathrm{Std}} \sum_{j_1,\ldots,j_d} \xi_{j_1,\ldots,j_d} \prod_{k=1}^{d} B_{j_k,S_k}(x_k;\tau_k).\]

xi is stored reshaped to basisSize, so in 2-D it is a matrix, in 3-D it is an array, and so on. The matrix-building helper is matrixForPointMatrix.