st.acr <- function(sim, diag=FALSE, upper = FALSE)
{
	library(vegan)
	dis <- 1 - sim
	#use "shortest" or "extended"
	edis <- as.matrix(stepacross(dis.yu, path = "shortest", toolong = 1))
	sim <- 1 - edis
	amax <- max(sim)
	amin <- min(sim)
	sim <- (sim-amin)/(amax-amin)
    sim2 <- sim[row(sim) > col(sim)]
    attr(sim2, "Size") <- nrow(sim)
    attr(sim2, "Labels") <- dimnames(sim)[[1]]
    attr(sim2, "Diag") <- diag
    attr(sim2, "Upper") <- upper
    attr(sim2, "call") <- match.call()
    class(sim2) <- "dist"
    return(sim2)
}