On Wed, Jul 18, 2012 at 06:02:27PM -0700, bilelsan wrote:
> Leave the Taylor expansion aside, how is it possible to compute with [R]:
> f(e) = e1 + e2 #for r = 1
> + 1/2!*e1^2 + 1/2!*e2^2 + 1/2!*e1*e2 #for r = 2, excluding e2*e1
> + 1/3!*e1^3 + 1/3!*e1^2*e2 + 1/3!*e2^2*e1 + 1/3!*e2^3 #for r = 3, excluding
> e2*e1^2 and e1*e2^2
> + ... #for r = k
> In other words, I am trying to figure out how to compute all the possible
> combinations as exposed above.
Hi.
For a general r, do you mean the following sum of products?
1/r! (e1^r + e1^(r-1) e2 + ... e1 e2^(r-1) + e2^r)
If this is correct, then try
f <- 0
for (r in 1:k) {
f <- f + 1/factorial(r) * sum(e1^(r:0)*e2^(0:r))
}
Hope this helps.
Petr Savicky.
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