splinef

A spline function \(F_T(t)\) for trends is specified by a set of \(n\) interpolating points:

• time values $$t_1, t_2, \ldots, t_n,$$

• and corresponding \(y\) values $$y_1, y_2, \ldots, y_n.$$

See also

stats::spline, makepar_F_spline