To view the source of (most) functions, simply type funcname without
parentheses: here, you get
> dmvt
function (x, delta, sigma, df = 1, log = TRUE, type = "shifted")
{
if (df == 0)
return(dmvnorm(x, mean = delta, sigma = sigma, log = log))
if (is.vector(x)) {
x <- matrix(x, ncol = length(x))
}
if (missing(delta)) {
delta <- rep(0, length = ncol(x))
}
if (missing(sigma)) {
sigma <- diag(ncol(x))
}
if (NCOL(x) != NCOL(sigma)) {
stop("x and sigma have non-conforming size")
}
if (!isSymmetric(sigma, tol = sqrt(.Machine$double.eps),
check.attributes = FALSE)) {
stop("sigma must be a symmetric matrix")
}
if (length(delta) != NROW(sigma)) {
stop("mean and sigma have non-conforming size")
}
m <- NCOL(sigma)
distval <- mahalanobis(x, center = delta, cov = sigma)
logdet <- sum(log(eigen(sigma, symmetric = TRUE, only.values =
TRUE)$values))
logretval <- lgamma((m + df)/2) - (lgamma(df/2) + 0.5 * (logdet +
m * logb(pi * df))) - 0.5 * (df + m) * logb(1 + distval/df)
if (log)
return(logretval)
return(exp(logretval))
}
Most of the functions in here you can see code for the same way: the
only ones you won't be able to are eigen, lgamma, log, exp, but these
methods are pretty well-documented and you shouldn't need to find code
for them. If you do, you'll need to read the underlying C.
Michael
On Sun, Mar 18, 2012 at 11:12 PM, statfan <irene_vr...@hotmail.com> wrote:
> Is there any way to know how the "dmvt" function computes the hypergeometric
> function needed in the calculation for the density of multivariate t
> distribution?
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/hypergeometric-function-in-mvtnorm-tp4483730p4483730.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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and provide commented, minimal, self-contained, reproducible code.
