MortSmooth.bbase {MortalitySmooth} | R Documentation |
This is an internal function of package MortalitySmooth
which
creates equally-spaced B-splines basis over an abscissa of data within
the function Mort1Dsmooth
.
MortSmooth.bbase(x, xl, xr, ndx, deg)
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. |
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
.
A matrix containing equally-spaced B-splines of degree deg
along x
for each column.
Carlo G Camarda
Eilers and Marx (2004). Splines, Knots, and Penalties. Unpublished manuscript.
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")