splint {funfits} | R Documentation |
Fits a piecewise 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.
splint(x, y, xgrid, derivative=0)
x |
The x values the 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. |
A vector consisting of the spline evaluated at the grid values.
See Additive Models by Hastie and Tibshriani.
spreg, sreg, tps
splint(ozone$x[,1],ozone$y,seq(min(ozone$x[,1]),max(ozone$x[,1]),,40)) -> fit # evaluate cubic spline to ozone at longitude values on grid of # longitude values