MortSmooth.bbase {MortalitySmooth}R Documentation

Construct B-spline basis

Description

This is an internal function of package MortalitySmooth which creates equally-spaced B-splines basis over an abscissa of data within the function Mort1Dsmooth.

Usage

MortSmooth.bbase(x, xl, xr, ndx, deg)

Arguments

x Vector for the abscissa of data.
xl Left boundary.
xr Right boundary.
ndx Number of internal knots minus one or number of internal intervals.
deg Degree of the splines.

Details

The function reproduce an algorithm presented by Eilers and Marx (2004) using differences of truncated power functions (see MortSmooth.tpower). The final matrix has a single B-spline for each of the [ndx + deg] columns. The number of rows is equal to the length of x.

Value

A matrix containing equally-spaced B-splines of degree deg along x for each column.

Author(s)

Carlo G Camarda

References

Eilers and Marx (2004). Splines, Knots, and Penalties. Unpublished manuscript.

See Also

MortSmooth.tpower.

Examples

x <- seq(0,1,length=100)
# B-splines basis of degree 1
B1 <- MortSmooth.bbase(x=x, xl=min(x), xr=max(x), ndx=10, deg=1)
matplot(x, B1, t="l", main="B-splines basis of degree 1")
# B-splines basis of degree 3
B3 <- MortSmooth.bbase(x=x, xl=min(x), xr=max(x), ndx=10, deg=3)
matplot(x, B3, t="l", main="B-splines basis of degree 3")

[Package MortalitySmooth version 1.0 Index]