R/pv.R

In gallagherj2008/SWAT: SWAT Assists Analysts in Visualizing and Understanding Shortened Web Link Data

pv <- function(FV, r, n = 5, digits = 2) {
  
   if(!is.atomic(FV)) {
     stop('FV must be an atomic vector')
   }
   
   if(!is.numeric(FV) | !is.numeric(r) | !is.numeric(n)) {
     stop('This function only works for numeric inputs!\n', 
          'You have provided objects of the following classes:\n', 
          'FV: ', class(FV), '\n',
          'r: ', class(r), '\n',
          'n: ', class(n))
   }
   
   if(r < 0 | r > .25) {
     message('The input for r exceeds the normal\n',
             'range for interest rates (0-25%)')
  }
  
  present_value <- FV / (1 + r)^n
  round(present_value, digits)
}