From: Gabor Grothendieck <ggrothendieck_at_gmail.com>

Date: Thu, 6 Dec 2007 18:42:06 -0500

R-help_at_r-project.org 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. Received on Thu 06 Dec 2007 - 23:45:41 GMT

Date: Thu, 6 Dec 2007 18:42:06 -0500

On Dec 6, 2007 6:13 PM, Emmanuel Charpentier <charpent_at_bacbuc.dyndns.org> wrote:

> Gabor Grothendieck a écrit :

*> > On Dec 6, 2007 3:26 PM, marciarr <marcia.rocha_at_gmail.com> wrote:
**>
**> [ Snip.... ]
**>
**> >> 2- how do I solve a simple equation? Considering the equation y= exp(-x)^12,
**> >> I would like to find the values of x for, for example, y=0.01, so
**> >> exp(-x)^12=0.01. How do I do that using R?
**> >> I know those a probably very, very simple questions, but for which I do not
**> >> seem to find the answer.
**> >
**> > Search between 0 and 1 for the root of the indicated function:
**> >
**> > uniroot(function(x) 0.1 - exp(-x)^12, 0:1)
**>
**> I beg your pardon ?
**>
**> I'd rather use high-school algebra/analysis :
**> log(exp(-x)^12)=log(0.01)
**> 12log(exp(-x)=log(0.01)
**> -12x=log(0.01)
**> x=-log(0.01)/12=log(100)/12
**>
**> Rushing for a sophisticated numerical tool without thinking for an
**> explicit solution is easy, fast, lazy (I do that every day ...), but
**> deprives you of the process of understanding the problem.
**>
*

The posting instructions ask for minimal code and its likely that the poster did not literally mean that that was the eventual problem.

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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. Received on Thu 06 Dec 2007 - 23:45:41 GMT

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