R: Calculate the knot averages of a B-spline basis.

knotave {SEL} | R Documentation

## Calculate the knot averages of a B-spline basis.

### Description

Calculates the knot averages of a B-spline basis.

### Usage

      knotave(knots, d)

### Arguments

`knots` | Knot Vector (with d+1 coincident knots on the boundaries).
`d` | Degree of the B-spline basis.

### Value

Numeric containing knot averages

### Author(s)

Bjoern Bornkamp

### References

Bornkamp, B. and Ickstadt, K. (2009). A Note on B-Splines for Semiparametric Elicitation. The American Statistician, 63, 373–377

Dierckx, P. (1993), Curve and Surface Fitting with Splines, Clarendon Press

### See Also

`SEL`

### Examples

    ## Example for calculation of a control polygon
    knts <- c(rep(0, 4), rep(1, 4))
    cf <- c(-1, -1, 1/2, 0)
    sq <- seq(0, 1, length = 101)
    N <- splineDesign(sq, knots = knts, ord = 4)
    res <- colSums(t(N)*cf)
    plot(sq, res, type = "l", ylim = c(-1, 0.6))
    kntAv <- knotave(knts, 3)
    lines(kntAv, cf, col = "red") # add control polygon

[Package SEL version 1.0-2 Index]