Computes the sum of second derivatives of the multivariate
inverse Gaussian density with respect to the data argument
x. The function is vectorized for more efficiency.
dmig_laplacian(x, xi, Omega, beta, scale = TRUE)an n vector
n by d matrix of quantiles
d vector of location parameters \(\boldsymbol{\xi}\), giving the expected value
d by d positive definite scale matrix \(\boldsymbol{\Omega}\)
d vector \(\boldsymbol{\beta}\) defining the half-space through \(\boldsymbol{\beta}^{\top}\boldsymbol{\xi}>0\)