Dear all, I have a general relationship, which can be easily solved using forward engineering model, y=f(x1, x2, x3) Now I know a distribution of y, how can I get the corresponding distributions for x1, x2, and x3? In another situation, if I know the distributions of y and x1, how can I obtain the corresponding distributions of x2 and x3? Are there some R packages for this inverse problem (or called back calculation)? Thanks a lot, Terry [[alternative HTML version deleted]]