The preceding equations can be expressed as matrix notation using the evaluation in a grid of the length M {a = t1 < ⋯ < tM = b} as X=CΨ,B=b′φ, where X is the matrix n × M with the evaluations of the curves in the grid, C is the matrix n × Kx with the coefficients of the representation in the basis and Ψ is the matrix Kx × M with the evaluations of the basis elements on the grid. Similarly, B is the matrix (1 × M) with the evaluation of the β parameter on the grid, φ is the matrix (Kβ × M) with the evaluations of the basis {φj} and b on the grid, is the vector of the coefficients of β in the basis.