R help - Aug 2011 - d, p, q, r - What are the math relations with each other of this functions?

Hi all,

Using the exponential distribution to exemplify: The dexp function is
the PDF (1) and pexp is the CDF (2), that is obtained integrating the
PDF. How can I get the qexp and the rexp? Considering that I have the
PDF, how this two are mathematically related to the PDF?

(1) ke^{-kx}
(2) 1-e^{kx}

Thanks in advance.

Read the documentation by typing ?qexp (or whatever other function) at the
command line.

But, since you asked and it won't take long to answer, the general pattern
is:

rDIST gives random numbers sampled from the distribution
dDIST gives the PDF
pDIST gives the CDF
qDIST gives the quantile function (which can be thought of as the inverse
CDF)

To see that last relationship, try

curve(qexp(pexp(x)) or curve(pexp(qexp(x))

Hope this helps, but really -- read the help first. I could get it if you
didn't get what qDIST was from the documentation, but you should have gotten
rDIST.

Happy R-ing,

Michael Weylandt

On Mon, Aug 22, 2011 at 8:55 AM, . . <xkziloj@gmail.com> wrote:
> Hi all,
>
> Using the exponential distribution to exemplify: The dexp function is
> the PDF (1) and pexp is the CDF (2), that is obtained integrating the
> PDF. How can I get the qexp and the rexp? Considering that I have the
> PDF, how this two are mathematically related to the PDF?
>
> (1) ke^{-kx}
> (2) 1-e^{kx}
>
> Thanks in advance.
>
> ______________________________________________
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