[R] Fitting spline using Pspline

guy33 david.reshef at magd.ox.ac.uk
Mon May 30 00:28:18 CEST 2011


Ravi,

Thanks so much!  You're right, smooth.spline does work on larger n.

Although, for some reason it's results are different (slightly less good?,
but I'm not sure).  For example, on the simple doppler function below,
sm.spline seems to be closer to the true function than smooth.spline:

x=array(0,1000)
y=array(0,1000)
for (i in 1:1000){
	x[i] = i/1000
	y[i] = (x[i]*(1-x[i]))^.5 * sin(2*pi*(1.05/(x[i]+.05)))
}
plot(x,y)

fit = sm.spline(x, y, norder=2, cv=FALSE)
lines(fit$x,fit$y)

fit2 = smooth.spline(x, y, cv=FALSE)
lines(fit2$x,fit2$y)


What do you make of that?
-guy33

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