Computes the design matrix for B-splines based on the
specified knots and evaluated at the values in x.
Usage
splineDesigncpp(
knots = NA_real_,
x = NA_real_,
ord = 4L,
derivs = as.integer(c(0))
)
Value
A matrix with dimensions
c(length(x), length(knots) - ord). Each row corresponds
to a value in x and contains the coefficients of the
B-splines, or the specified derivatives, as defined by the
knots and evaluated at that particular value of x.
The total number of B-splines is length(knots) - ord,
with each B-spline defined by a set of ord consecutive knots.
Arguments
knots
A numeric vector specifying the positions of the knots,
including both boundary and internal knots.
x
A numeric vector of values where the B-spline functions
or their derivatives will be evaluated. The values of x
must lie within the range of the "inner" knots, i.e., between
knots[ord] and knots[length(knots) - (ord - 1)].
ord
A positive integer indicating the order of the B-spline.
This corresponds to the number of coefficients in each piecewise
polynomial segment, where ord = degree + 1.
derivs
An integer vector specifying the order of derivatives
to be evaluated at the corresponding x values. Each value
must be between 0 and ord - 1, and the vector is
conceptually recycled to match the length of x.
The default is 0, meaning the B-spline functions themselves
are evaluated.