[R] Spline function

Bert Gunter bgunter@4567 @end|ng |rom gm@||@com
Wed Aug 15 00:22:38 CEST 2018

If I understand correctly, not in general possible.

Suppose for a bunch of different x's the y's are all constant =0. What x
would correspond to y = 1.

Or suppose (x,y) pairs trace a sine function over several periods. Then
there is no unique x corresponding to y = .5, say.

Perhaps if you more explicitly specified the nature of your problem (e.g.
is y monotonic in x?) some assistance might be provided.


Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Tue, Aug 14, 2018 at 8:48 AM, Tania Morgado Garcia <tmg1970 using gmail.com>

>  Hello everyone. I'm new to R and I'm using spline functions. With the
> command splinefun (x, y) I get the function of interpolating the values x
> and y. Later, I can evaluate that function for values of x by obtaining the
> respective values of y. The point is that I need the inverse operation,
> with the function, for a value of Y I need to know the value of x. Could
> you please help me?
> A cordial greeting
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