n.interval <- function(a,b,mu=0,sigma=1)
{
return(abs(pnorm(a,mu,sigma)-pnorm(b,mu,sigma)))
}

n.tail <- function(x,mu=0,sigma=1)
{
return(1 - pnorm(abs((x-mu)/sigma)))
}

n.relative.tail <- function(cutoff,mu.a,sigma.a,mu.b,sigma.b)
{
return(n.tail(cutoff,mu.a,sigma.a)/n.tail(cutoff,mu.b,sigma.b))
}