compound_interest.R

compound <- function(start, growthrate_percent, fees_percent, years=15) {
  amount <- start
  growthrate_proportion <- growthrate_percent/100
  fees_proportion <- fees_percent/100
  yearly_vals <- rep(NA, years)
  for(year in 1:years) {
    amount <- amount*(1+growthrate_proportion) - amount*fees_proportion
    yearly_vals[year] <- amount
  }
  plot(x=1:years,y=yearly_vals, pch=16, cex=2, ylab="total value in dollars", xlab="year", main=sprintf("growing at %.3f%% with fees of $%.3f%%\nstarting value: $%.2f\nending value: $%.2f",growthrate_percent, fees_percent,start, amount))
  #plot(x=1:years,y=yearly_vals,add=T, type=line())
  return(yearly_vals)
}

compound(start=100, growthrate_percent = 5, fees_percent = 0, years = 10)