gistfile1.r

interest <- function (balance, r)
{
    cash_flow <- c(0,diff(c(0,balance)))
    for (i in 2:length(cash_flow))
        cash_flow[i] <- (cash_flow[i] + cash_flow[i-1]) * (1 + r)
    cash_flow[2:(length(balance)+1)] - balance
}

gen_nsweep <- function (N, days=31)
{
    M <- rep(1000, days)
    for (i in 1:N)
    {
        k <- floor(days * (i / (N+1)))
        M[k:days] <- M[k:days] - (M[1]/N)
    }
    return (M)
}

days<-31
r<-0.01
plot(sapply(1:days, function(i) interest(gen_nsweep(i, days), r)[days]), type='s', xlab='N sweeps', ylab='Interest $')