Alternatively, how about the following:
library(polynom)
coefficients(polynomial(c(1,1,1))^3)
[1] 1 3 6 7 6 3 1
hope this helps. spencer graves
Gabor Grothendieck wrote:
From: Peter Yang <[EMAIL PROTECTED]>
I would like to get the coefficients of x^0, x^1, x^2, . , x^6 from
expansion of (1+x+x^2)^3.
# modification of DD in example(D) to support 0th derivative
DD <- function(expr,name, order = 0) {
if(order == 0)
expr
else DD(D(expr, name), name, order - 1)
}
# take symbolic derivatives, evaluate at 0 and divide by factorial n
sapply(0:6, function(i) eval(DD(e,"x",i),list(x=0)))/factorial(0:6)
By the way, e in the above is your expression, in this case:
e <- expression((1+x+x^2)^3)
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Spencer Graves, PhD, Senior Development Engineer
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