If it is in a data frame with the variables as columns try
f <- cbind(a*b, b*c, c*d)
sapply(f, function(x)var(x))

On Fri, Jul 25, 2008 at 5:06 PM, Zhang Yanwei - Princeton-MRAm <
YZhang@munichreamerica.com> wrote:

> Hi all,
>   I have n independent variables A_1, A_2, A_3,......,A_n, and each with
> known variances var(A_1), var(A_2),..., but unknown mean. How can I get the
> approximation of the variance of the product of the variables using
> numerical computation, i.e. var(A_1*A_2*A_3*.....*A_n)? Thanks.
>
> Sincerely,
> Yanwei Zhang
> Department of Actuarial Research and Modeling
> Munich Re America
> Tel: 609-275-2176
> Email: yzhang@munichreamerica.com<mailto:yzhang@munichreamerica.com>
>
>
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>
> ______________________________________________
> R-help@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.
>



-- 
Let's not spend our time and resources thinking about things that are so
little or so large that all they really do for us is puff us up and make us
feel like gods. We are mammals, and have not exhausted the annoying little
problems of being mammals.

-K. Mullis

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