"precision matrix" associated with the integration grid. When
building a sparse integration grid for a density, prec is often
the negative of the hessian at the mode.
level
accuracy level. This is typically number of grid points for the
underlying 1D quadrature rule. [description from mvQuad::createNIGrid]
quadError
provide additional information about the grid points and
integration weights for the quadrature rule with level-1. This
information can facilitate approximating the quadrature error.
prec.chol
Upper-triangular Cholesky decomposition of precision matrix.