[R] dw statistic

[Rui Cerqueira]

  Hello Uwe

  First, I want to thank you for spending your time replying to my mail. I'm 
very impressed with the speed that my question was answered.
I'm new at R (about two weeks) and reading your mail made me realize that it 
was indeed a question of vectors of different lengths. I thinked that I 
could create a function ("carfun") without creating a "x" vector, since the 
only purpose of that function is to be integrated right away in the same "x" 
(I re-posted my function again at the end).
  But now I have another question: since "x" must be of "(dw-eigen)"'s 
length, how can I create a polynom in "x" of variable degree 
(=length("(dw-eigen)")) to be integrated? The computation of the exact 
p-value of DW is a hard one (since it depends on X matrices and the formula 
is a bit complicated), but the DW statistic is a valuable calculation in 
econometrics. The package "lmtest" has a function "dwtest", but it doesn't 
give any p-value.
  Thank you once more.



> > »dwf0 <- function(dw,eigen) { carfun <- function(x) {
> > 
>(prod(1+2*(eigen-dw)*1i*x)^(-1/2)-prod(1-2*(eigen-dw)*1i*x)^(-1/2))/(1i*x) 
>}
> > ; 1/2+integrate(f=carfun,lower = 0,upper = Inf,
> > subdivisions=10000)$value/(2*pi) }


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