function(price, t = 1)
{
#compute NORMALIZED UNCONDITIONAL t DAYS RETURNS
	n <- length(price)
	normret <- rep(0, n - t)
	for(i in 1:(n - t))
		normret[i] <- (price[i + t]/price[i])
	E <- mean(normret)
	S <- sqrt(var(normret))
	for(i in 1:(n - t))
		normret[i] <- ((normret[i] - E)/S)
	return(normret)
}
