iknots {bspline} R Documentation

## Estimate internal knot positions equalizing jumps in n-th derivative

### Description

Normalized total variation of n-th finite differences is calculated for each column in y then averaged. These averaged values are fitted by a linear spline to find knot positions that equalize the jumps of n-th derivative.
NB. This function is used internally in (fit)smbsp() and a priori has no interest to be called directly by user.

### Usage

iknots(x, y, nki = 1L, n = 3L)


### Arguments

 x Numeric vector y Numeric vector or matrix nki Integer scalar, number of internal knots to estimate (1 by default) n Integer scalar, polynomial order of B-spline (3 by default)

### Value

Numeric vector, estimated knot positions

[Package bspline version 2.1 Index]