Hi all, I am using the fMultivar package for calculating probabilities of bivariate normal distribution. I use the manual's example to understand what is going on, but let's take it for smaller dimensions of x and y: ## Bivariate Normal Density: x = c(0.3,10) y = c(-10,0.2) X = grid2d(x,y) z = pnorm2d(X$x, X$y, rho = 0.5) Z = list(x = x, y = y, z = matrix(z, ncol = length(x))) persp(Z, theta = -40, phi = 30, col = "steelblue") What does the grid2d() command do? In the Z- result in the matrix, I really cannot figure out where the 4 probabilities are referring to. Can anyone enlighten me? Thank you for your time! Ismini