[R] About an integral univariate problem

[R. Michael Weylandt]

How about adding an additional argument to fun?

R> fun <- function(x, y) exp(-x)*sum(y^x)
R> y <- c(2,3,5)
R> integrate(fun, 0, 3, y)
[1] 346.853 with absolute error < 3.9e-12
Michael

On Tue, Oct 18, 2011 at 10:01 AM, Freddy Hernandez Barajas
<fhernanb at gmail.com> wrote:
> Hello all R users
>
> I want to calculate this univariate integral:
> exp(-x)*sum(y^x)  respect to x  from 0 to 3  where y is a vector y=(2,3,5).
> In fact, the original y vector has a large number of elements but I propose
> with 3 elements.
>
> I know that I can resolve this problem doing
>
> fun <- function(x) exp(-x)*(2^x+3^x+5^x)
> integrate(fun,0,3)
>
> When the y vector has a large number of elements the last solution is not
> possible,
> if I use this another way I can not obtain the true answer
>
>   y <- c(2,3,5)
> fun1 <- function(x) exp(-x)*sum(y^x)
> integrate(fun1,0,3)
>
> Someone could give me a help with the problem?
> Thanks.
>
>
> Freddy Hernández Barajas
>
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>
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