Calculate the knot averages of a B-spline basis.

Description

Calculates the knot averages of a B-spline basis.

Usage

  knotave(knots, d)

Arguments

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

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

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> library(SEL)
Loading required package: splines
Loading required package: quadprog
Loading required package: lattice
> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/SEL/knotave.Rd_%03d_medium.png", width=480, height=480)
> ### Name: knotave
> ### Title: Calculate the knot averages of a B-spline basis.
> ### Aliases: knotave
> 
> ### ** 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
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>