Returns the piecewise polynomial form of the Catmull-Rom cubic spline interpolating f at the points x. If the input v is supplied it will be interpreted as the values of the tangents at the extremals, if it is missing, the values will be computed from the data via one-sided finite difference formulas. See the wikipedia page for "Cubic Hermite spline" for a description of the algorithm.
See also: ppval.
Package: splines