vif.lmrob <- 
function (mod, ...) 
{
    if (any(is.na(coef(mod)))) 
        stop("there are aliased coefficients in the model")
    v <- vcov(mod)
    assign <- attributes(model.matrix(mod))$assign
    if (names(coefficients(mod)[1]) == "(Intercept)") {
        v <- v[-1, -1]
        assign <- assign[-1]
    }
    else warning("No intercept: vifs may not be sensible.")
    terms <- labels(terms(mod))
    n.terms <- length(terms)
    if (n.terms < 2) 
        stop("model contains fewer than 2 terms")
    R <- cov2cor(v)
    detR <- det(R)
    result <- matrix(0, n.terms, 3)
    rownames(result) <- terms
    colnames(result) <- c("GVIF", "Df", "GVIF^(1/(2*Df))")
    for (term in 1:n.terms) {
        subs <- which(assign == term)
        result[term, 1] <- det(as.matrix(R[subs, subs])) * det(as.matrix(R[-subs, 
            -subs]))/detR
        result[term, 2] <- length(subs)
    }
    if (all(result[, 2] == 1)) 
        result <- result[, 1]
    else result[, 3] <- result[, 1]^(1/(2 * result[, 2]))
    result
}