rmt | R Documentation |
Random number generation from the multivariate-t distribution.
rmt(n = 1, mean = rep(0, nrow(Sigma)), Sigma = diag(length(mean)), eta = .25)
n |
the number of samples requested |
mean |
a vector giving the means of each variable |
Sigma |
a positive-definite covariance matrix |
eta |
shape parameter (must be in |
The function rmt
is an interface to C routines, which make calls to
subroutines from LAPACK. The matrix decomposition is internally done using
the Cholesky decomposition. If Sigma
is not non-negative definite then
there will be a warning message.
This parameterization of the multivariate-t includes the normal distribution
as a particular case when eta = 0
.
If n = 1
a vector of the same length as mean
, otherwise a
matrix of n
rows of random vectors.
Devroye, L. (1986). Non-Uniform Random Variate Generation. Springer-Verlag, New York.
rt
# covariance matrix Sigma <- matrix(c(10,3,3,2), ncol = 2) Sigma # generate the sample y <- rmt(n = 1000, Sigma = Sigma) # scatterplot of a random bivariate t sample with mean vector # zero and covariance matrix 'Sigma' par(pty = "s") plot(y, xlab = "", ylab = "") title("bivariate t sample (eta = 0.25)", font.main = 1)
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