R-beta: spline problems(?)

A. Tsiolakidis (tsioltas@cs.keele.ac.uk)
Tue, 07 Apr 1998 03:30:33 +0100


Date: Tue, 07 Apr 1998 03:30:33 +0100
From: "A. Tsiolakidis" <tsioltas@cs.keele.ac.uk>
To: r-help@stat.math.ethz.ch
Subject: R-beta: spline problems(?)

Hi,

I am a total beginner with this whole thing so please have patience!

I am trying to run an S-plus program with a certain line:
	spline(1:nrow(y), y[,1],n=100);

This crashes with:
	Error: NAs in foreign function call (arg 8)

Apparently, this is caused by the last command of spline:
	u <- seq(xmin, xmax, length.out = n)
        .C("spline_eval", z$method, length(u), x = u, y = double(n), 
                z$n, z$x, z$y, z$b, z$c, z$d)[c("x", "y")]
}

Now, I can cause that error with: spline(1:10,1:10)
So, there  is a whole class of problems for which spline refuses to
compute anything - is this the correct behaviour? E.g.,
	spline(1:10,(1:10)/2.5) #it is alright, but ...
	spline(1:10,(1:10)/2)   # this has the "NAs.." problem

Finally, I am almost sure that the y matrix in my program has quite
normal values, i.e. values that should allow for meaningful
interpolation.
Anybody knows what this all is about?

Thanks,

Tasos T.
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