| splineDesign {splines} | R Documentation |
Design Matrix for B-splines
Description
Evaluate the design matrix for the B-splines defined by knots
at the values in x.
Usage
splineDesign(knots, x, ord = 4, derivs)
spline.des(knots, x, ord = 4, derivs)
Arguments
knots |
a numeric vector of knot positions with non-decreasing values. |
x |
a numeric vector of values at which to evaluate the B-spline
functions or derivatives. The values in |
ord |
a positive integer giving the order of the spline function. This is the number of coefficients in each piecewise polynomial segment, thus a cubic spline has order 4. Defaults to 4. |
derivs |
an integer vector of the same length as |
Value
A matrix with length( x ) rows and length( knots ) - ord
columns. The i'th row of the matrix contains the coefficients of the
B-splines (or the indicated derivative of the B-splines) defined by
the knot vector and evaluated at the i'th value of x.
Each B-spline is defined by a set of ord successive knots so
the total number of B-splines is length(knots)-ord.
Note
The older spline.des function takes the same arguments but
returns a list with several components including knots,
ord, derivs, and design. The design
component is the same as the value of the splineDesign
function.
Author(s)
Douglas Bates and Bill Venables
Examples
splineDesign(knots = 1:10, x = 4:7)