# [R] How to calculate the x to assymptotic value and curve inflection .

Ronaldo Reis Jr. chrysopa at insecta.ufv.br
Fri May 2 15:32:22 CEST 2003

```Sorry, my answer is a bit confused.

I try to explain.

look this code:

> curve(115.251 - 118.69 * exp(-0.123517*x),from=0,to=100)
> lines(c(75,75),y=c(-10,115.251),col="red")
> lines(c(-10,75),y=c(115.251,115.251),col="red")
> lines(c(20,20),y=c(-10,105),col="blue")
> lines(c(-10,20),y=c(105,105),col="blue")

All values of this points are fictition, only curve values are real and the y
assyntotic value.

in red is the  y assyntotic and your minimal x, the first value of x that y is
assyntotic value.
The y assyntotic is easy, it is the first parameter = 115.251. To calculate
the value of minimal x, I can make a program that increment x, and when y
value is repeated, I know what is the minimal x. Exist another mean to make
this?

The another point (blue) is more difficult. I try to explain. The curve
velocity is very huge before this blue point than after this point. This
point is something like the inflection point in a X^2 function. Biologically
this point maybe very important. I try to calculate this with the firt
derivate, but I cant resolve this.

Exist another solution for this?

Thanks for all

Inte
Ronaldo

Em Qua 30 Abr 2003 16:57, Douglas Bates escreveu:
> I think you need to refine your questions.  To me, the answers to the
> questions that you asked are: "x = Inf (by definition)" and "there
> isn't an inflection point".  I don't think those are what you had in
> mind.
>
> "Ronaldo Reis Jr." <chrysopa at insecta.ufv.br> writes:
> > Hi,
> >
> > I have this non-linear function:
> >
> > y=115.251 - 118.69 * exp(-0.123517*x)
> >
> > I try to discovery the x value for the assyntoptic value of y
> > and the x value where the behavior of curve change, the inflection
> > point.
> >
> > How to make this? Is possíble to make this on R?
> >
> > Thanks
> > Ronaldo
>
--
A necessidade nunca fez bons negócios.
-- Benjamin Franklin
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