getbasismatrix: Values of Basis Functions or their Derivatives

In fda: Functional Data Analysis

Values of Basis Functions or their Derivatives

Description

Evaluate a set of basis functions or their derivatives at a set of argument values.

Usage

getbasismatrix(evalarg, basisobj, nderiv=0, returnMatrix=FALSE)

Arguments

evalarg	a vector of arguments values.
basisobj	a basis object.
nderiv	a nonnegative integer specifying the derivative to be evaluated.
returnMatrix	logical: If TRUE, a two-dimensional is returned using a special class from the Matrix package.

Value

a matrix of basis function or derivative values. Rows correspond to argument values and columns to basis functions.

See Also

eval.fd

Examples

##
## Minimal example:  a B-spline of order 1, i.e., a step function
## with 0 interior knots:
##
bspl1.1 <- create.bspline.basis(norder=1, breaks=0:1)
m <- getbasismatrix(seq(0, 1, .2), bspl1.1)

# check
m. <- matrix(rep(1, 6), 6,
    dimnames=list(NULL, 'bspl') )

all.equal(m, m.)


##
## Date and POSIXct
##
# Date
July4.1776    <- as.Date('1776-07-04')
Apr30.1789    <- as.Date('1789-04-30')
AmRev         <- c(July4.1776, Apr30.1789)
BspRevolution <- create.bspline.basis(AmRev)
AmRevYears    <- as.numeric(seq(July4.1776, Apr30.1789, length.out=14))
AmRevMatrix   <- getbasismatrix(AmRevYears, BspRevolution)
matplot(AmRevYears, AmRevMatrix, type='b')

# POSIXct
AmRev.ct    <- as.POSIXct1970(c('1776-07-04', '1789-04-30'))
BspRev.ct   <- create.bspline.basis(AmRev.ct)
AmRevYrs.ct <- as.numeric(seq(AmRev.ct[1], AmRev.ct[2], length.out=14))
AmRevMat.ct <- getbasismatrix(AmRevYrs.ct, BspRev.ct)
matplot(AmRevYrs.ct, AmRevMat.ct, type='b')

fda documentation built on May 31, 2023, 9:19 p.m.