On Sat, 23 Aug 2008, wangyq wrote:
If ''N'' is a discrete random variable taking values on some subset of
the non-negative [[integer|integers]], {''0,1, ...''}, then the
''probability-generating function'' of ''N'' is defined as:
:<math>G(x) = \textrm{E}(x^N) = \sum_{n=0}^{\infty}f_N(n)x^n,</math>
where ''f<sub>N</sub>'' is the probability mass function of ''N''.
Note that the equivalent notation ''G''<sub>''N''</sub> is sometimes
used to distinguish between the probability-generating functions of
several random variables.
I don't believe there are tools for this unfortunately. However, as for
LaTeX math, try inserting the text into a LyX document. Then mark the
math bit and press Ctrl-m. This will turn it into a formula.
HTH
/Christian
--
Christian Ridderström, +46-8-768 39 44 http://www.md.kth.se/~chr
