>>>>> "AOlinto" == Antonio Olinto <[EMAIL PROTECTED]>
>>>>> on Mon, 7 Aug 2006 19:49:42 -0300 writes:
AOlinto> Hi,
AOlinto> I'd like to find which values of x will give me a y.
AOlinto> In other words, in the example of a gaussian curve, I want to find
the values of
AOlinto> x that will give me a density, let's say, of 0.02.
AOlinto>
curve(((1/(sqrt(2*pi)*10))*exp(-((x-50)^2)/(2*10^2))),xlim=c(0,100))
In other words, you are trying to *invert a function*
numerically, i.e.,
find x such that f(x) = y0
Now, this is trivially the same as finding the "root" (or
"zero") of the function f~(x) = f(x) - y0
==> Use *the* R root finding function :
uniroot() [or polyroot() if f(.) is a polynomial]
Martin Maechler, ETH Zurich
______________________________________________
[email protected] 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.
