Figure: The figure contains two spline curves consisting of one patch (build out of six scaled basis functions). The basis functions are drawn with dashed lines. Taking {0,1,2,2,1,0} (crosses in the graph) to weight the basis functions the curve drawn with rounds results. The curve with blocks presents the spline-approximation of the function f(x) = 8x(1-x) + noise (uniformous, mean = 0, standard deviation = 0.1).
The coefficients of the basis functions are estimated via a least squares fit: {-50,-11,3.6,4.3,-13,-41} with corresponding standard deviations: { 30, 4, 1.8, 1.8, 4, 30}.