R help - Jul 2006 - Calculate x-values from a spline

Hello,

I calculate splines from messured points(x,y) of an unknown function f(x).
e.g.
x <- c(0.004115, 0.012345, 0.037037, 0.111110, 0.333330, 1.000000)
y <- c(37, 50, 45, 60, 50, 66)
w <- c(0.8540541, 0.8320000, 0.8822222, 0.7983333, 0.8220000, 0.8151515) as
weights
f <- smooth.spline(x,y,w)

Now I have y-values and want to calculate the x-value(s) from this spline.
There is no further limitation to the spline, like monotonicity or anything
else..

Does anyone know how to do this ?

Gunther



gunther.hoening at ukmainz.de

Gunther H?ning a ?crit :
> Hello,
> 
> I calculate splines from messured points(x,y) of an unknown function f(x).
> e.g.
> x <- c(0.004115, 0.012345, 0.037037, 0.111110, 0.333330, 1.000000)
> y <- c(37, 50, 45, 60, 50, 66)
> w <- c(0.8540541, 0.8320000, 0.8822222, 0.7983333, 0.8220000, 0.8151515)
as
> weights
> f <- smooth.spline(x,y,w)
> 
> Now I have y-values and want to calculate the x-value(s) from this spline.
> There is no further limitation to the spline, like monotonicity or anything
> else..
> 
> Does anyone know how to do this ?
Perhaps this ?

finv = splinefun(f$y,f$x)
> 
> Gunther
> 
> 
> 
> gunther.hoening at ukmainz.de
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
> 
> 
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