splint {fields}R Documentation

Cubic spline interpolation


A fast, FORTRAN based function for cubic spline interpolation.


splint(x, y, xgrid, derivative=0)


x The x values that define the curve or a two column matrix of x and y values.
y The y values that are paired with the x's.
xgrid The grid to evaluate the fitted cubic interpolating curve.
derivative Indicates whether the function or a a first or second derivative should be evaluated.


Fits a piecewise interpolating cubic polynomial to the x and y values assuming that the second and third derivatives are zero at the range of the x values. For this reason extrapolation outside the range of the x values will be a linear function.


A vector consisting of the spline evaluated at the grid values.


See Additive Models by Hastie and Tibshriani.

See Also

sreg, Tps


x<- seq( 0, 120,,200)

splint(rat.diet$t, rat.diet$trt,x )-> y

plot( rat.diet$t, rat.diet$trt)
lines( x,y)
#( this is weird!)

[Package fields version 3.3.1 Index]