init.quad to generate a quadrature grid, and eval.quad to evaluate the integral.
Evaluation is performed with Gauss-Hermite quadrature, with a prior distribution that can be specified to any multivariate normal.
Additionally, the grid can be adapted to any multivariate normal distribution - that is known to be close(r)
to the posterior distribution under evaluation.
Bock, R. D., & Mislevy, R. J. (1982). Adaptive EAP Estimation of Ability in a Microcomputer Environment. Applied Psychological Measurement, 6(4), 431-444. http://doi.org/10.1177/014662168200600405
init.quad, eval.quad