vif.lm <- function(object, ...) {
  V <- summary(object)$cov.unscaled
  Vi <- crossprod(model.matrix(object))
        nam <- names(coef(object))
  if(k <- match("(Intercept)", nam, nomatch = F)) {
                v1 <- diag(V)[-k]
                v2 <- (diag(Vi)[-k] - Vi[k, -k]^2/Vi[k,k])
                nam <- nam[-k]
        } else {
                v1 <- diag(V)
                v2 <- diag(Vi)
                warning("No intercept term detected. Results may
surprise.")
        }
        structure(v1*v2, names = nam)
}